Memory Management Essay Example for Free

Memory Management Essay The difference between Windows and Linux memory management starts with understanding the requirements of memory management in today’s multiprogramming systems. Memory management requirements are relocation, protection, sharing, local organization, and physical organization. These requirements play a vital role in the processing speed response when using the computer. Windows and Linux have several similarities in regards to memory management but also differ especially with Windows being a sophisticate system and Linux being open sourced. â€Å"Linux shares UNIX characteristics but has its own features and is very complex† (Stallings, 2012, p. 384). Linux virtual memory uses a three- level page structure. The first part is the page structure which is an active process having the size of one page. The entry goes to the page directory and the page directory must be in the main memory to be active. Next is the page middle directory which can span multiple pages. Each entry will point to one page of the table. Last is the page table and refers to one virtual page of the process. A virtual address is used consisting of four fields which are the index into the page directory, index into the page middle directory, index into the page table, and the offset in the selected page of memory. The table structure was designed for 64-bit Alpha processor and is independent. Linux uses the buddy system for efficiency of reading in and writing out pages to and from memory. The buddy system splits and merges pages which are allocated and deallocated in the main memory. The page replacement algorithm in Linux deals with a simple clock which gives each page an age variable. The more times the page is accessed, the age variable is increased. A page that is old would be replaced since it has not been accessed in quite a long time. Linux kernel memory allocation manages the main memory page frames which allocates and deallocates frames for the virtual memory management. When the minimum amount of allocation is less than a page, Linux uses a slab allocation for these smaller chunks making the system more efficient. Windows memory manager is designed to use 4 to 64 Kbytes page sizes and controls how memory is allocated. On 32-bit systems, the Windows process  shows a 32-bit address which allows 4 Gbytes of virtual memory for each process which half is for the operating system and half is for the virtual address space when running in kernel-mode. With the introduction of 64-bit, systems can run more efficiently with larger memory intensive programs. Windows paging can make use of the entire space which can then be brought into the main memory. The operating system manages the address in three regions; available references the address not currently used, reserved for setting aside the process through the virtual memory manager, and committed address for processes to access virtual memory page. When virtual memory is high, the processes increase, and when they are low, older pages are swapped out. In conclusion, Windows and Linux have a few similarities. Both swaps out older pages that are no longer needed to improve the processes Window memory management is more secure and performance orientated, but is more complex. Linux is simpler and easier to maintain but is not secured due to being open sourced and need improvement. Linux was originated in a hacker’s environment while Windows is in a commercial environment. Windows has more effort through design and Linus was favored for simplicity. Each one has their own positives and negatives and the final decision is what system is he and she more comfortable with. References Stallings, W. (2012). Operating Systems: Internals and Design Principles (7th ed.). Retrieved from The University of Phoenix eBook Collection database.

Solenoid Operated Piston Pump Engineering Essay

Solenoid Operated Piston Pump Engineering Essay This project is aimed at analysing and designing a solenoid operated piston pump which is capable of delivering solution (this report assumes water) at a flow rate of 1 litre/min. However, the customer usage requires the flow rate to remain between 0.9 and 1.1 litre/min at an ambient pressure of about 1 bar. The operation mode of the piston pump is described below using the diagram: OscillPistonPump Fig 1.1 Solenoid Operated Piston Pump1 The solenoid coil (4) generates an electromagnetic field by the single wave diode rectified current flowing through the coil. Each current pulse moves the piston (5) against the pressure spring (3). This movement reduces the volume in the suction chamber causing an increase in pressure (P a 1/V), which opens the valve (6) in the piston, thereby allowing the liquid to run into the pressure side. When the current acting on the solenoid pulse is off, the pressure spring pushes back the piston toward the pressure side. The increase of pressure caused by the piston movement closes the piston valve (6) and the liquid flows through the valve (7) set in the pressure connection (8) and into the pressure pipe. The piston movement also simultaneously increases the volume in the suction chamber, thereby reducing the pressure below the chamber. The low pressure in the suction chamber opens the valve (2) set in the suction connection (1), and the liquid is sucked into the pump and the cycle starts again. The piston size and the length of its displacement define the flow rate. The pump will run without damage when the liquid flow is stopped momentarily1. This design concentrated on the piston, suction chamber and pressure springs design. Although references were made to the valves and solenoid force, engineering analysis were not carried out on them. CHAPTER 2 INITIAL ENGINEERING DESIGN ANALYSIS This section considered the engineering analysis of the operation of the piston pump to achieve the require specifications. The given specifications are; Flow rate Q = 1 Lit/min Frequency F = 60 cycles/sec Ambient Pressure = 1 bar Using the above specifications, the length of stroke of the piston, which is also termed as the â€Å"Swept Volume†, can be calculated using the relation below: Q = Volumetime=Volume Ãâ€"frequency = Ï€ d2 L4 Ãâ€"f ∠´L= 4QÏ€d2f Where: Q = Flow Rate =1 lit/min= 1.667 Ãâ€"104 mm3/sec f = Frequency (cycles/sec) L = Length of stroke/Swept volume (mm) d = Diameter of piston/suction chamber (mm) The diameter was varied from 1 to 20 mm and the corresponding lengths of stroke were obtained at different frequencies of 40, 45, 50, 55 and 60 cycles/sec. The results obtained were plotted (See appendix 1). After careful look, the frequency at 40 cycle/sec, so subsequent calculations would be based on this. It was also noticed that reasonable pair of dimensions of the diameter and length occurred around the diameters 5-10mm, therefore subsequent calculations were based on this range. 2.1 LOAD ANALYSIS The load analysis was carried out on each component designed as indicated below: A. Piston: The load analysis on the piston was done by isolating the piston and analysing the forces acting it. The different forces acting on the piston are as shown below: Force on piston causing acceleration Magnetic force from solenoid coil Resultant spring force Kinematic frictional force Gravitational force Resultant hydraulic force (including assumed viscous effect) This is assuming that atomic, initial static frictional force and temperature effects are negligible. The force analyses were carried out considering three different cases under which the pump operation can undergo. The intake and ejection strokes were also analysed separately to reduce complications. The difference between the intake and ejection stroke is that, the magnetic force from the solenoid is zero during ejection, because the solenoid is off: Case I: This is when the piston pump is used horizontally, that is, it is used to pump fluid on the same datum. This means that the gravitational effect and the height difference in the hydraulic force will be zero. The relationship between the forces will therefore be: Intake stroke: Force causing motion = Force from solenoid Resultant spring force Resultant hydraulic force Frictional force Ejection stroke: Force causing motion = Resultant spring force Resultant hydraulic force Frictional force Case II: This considered the case when the pump is used to transfer fluid from a higher level to a lower level. This means that the gravitational effect will favour the direction of flow therefore reducing the force needed to drive the piston. The relationship between the forces will therefore be: Intake stroke: Force causing motion = Force from solenoid Resultant spring force Resultant hydraulic force Frictional force Gravitational force Ejection stroke: Force causing motion = Resultant spring force Resultant hydraulic force Frictional force + Gravitational force Case III: This considered the case when the piston pump is used to deliver fluid from a lower level to a higher level. The difference between this case and case II is in the gravitational effect and the datum difference in the hydraulic effect. The design load analysis was done under this circumstance because pumps are usually used for this particular purpose. Even with this design concept, the pump can still be used for other cases, but it might deliver fluid at a higher flow rate, which could still be in the boundaries of the given tolerance of the flow rate. The relationship between the forces will therefore be: Intake stroke: Force causing motion = Force from solenoid Resultant spring force Resultant hydraulic force Frictional force + Gravitational force Ejection stroke: Force causing motion = Resultant spring force Resultant hydraulic force Frictional force Gravitational force. The different forces were calculated as follows using the free body diagram of the piston shown below: Figure 2.1 Boundary conditions of intake and ejection strokes Force from solenoid coil= Fs Force on piston causing motion = Mpa Where Mp = mass of piston kg and a = acceleration of piston (mm/s2) Mp= Ï  Ãâ€"V Ï  = Density of material (Stainless steel) =8Ãâ€"10-6 (kg/mm3) V=Volume of fluid displced in one stroke mm3= Q Ãâ€"t= Qf where f=45 cycles/sec=90 strokes/sec (2 strokes=1 cycle) Mp= Ï  Ãâ€" Qf=8Ãâ€"10-6 Ãâ€" 1.667 Ãâ€"10490=1.482Ãâ€"10-3 From law of motion; v2= u2+ 2aS u = 0 ∠´a=v22S Also v= St= S Ãâ€"f v=Velocity (mm/s) and S= L=Length of stroke (mm) ∠´a=L Ãâ€"f22L= L Ãâ€" f22= L Ãâ€" 9022 The length was varied from 5 to 10 mm, and different accelerations were obtained (See appendix 2). Resultant spring force = K2∆x- K1∆x= ∆xK2- K1= ∆x∆K Where K1 and K2=Stiffness of springs 1 and 2 respectively (N/mm) ∆x=L=Stoke length (mm) Kinematic frictional force = ÃŽ ¼kÃâ€"N= ÃŽ ¼kÃâ€"Mpg Where ÃŽ ¼k=Coefficient of kinematic friction N=Normal force= Mpg g=acceleration due to gravity=9810 mm/s2 Gravitational force = Mpg Hydraulic force = Total Change in Pressure ∆P (N/mm2)Surface Area of Piston A (mm2) From Bernoulllis equation   P1Ï g+ V122g+ Z1= P2Ï g+ V222g+ Z2 ∆P= P1-P2=Ï V22-V122+ ∆ZÏ g Q= A1V1= A2V2 ,   then V2= QA2= A1V1A2 and V1= QA1 ∆P= Ï A1V1A22-V122+ ∆ZÏ g= V12Ï 2 A1A22- 1+ ∆ZÏ g ∆P= Ï  Q22A12A1A22- 1+ ∆ZÏ g Where Q= Flow rate (mm3/s) , Ï  =density of water =1Ãâ€"10-6 (kg/mm3) A1and A2=Area mm2   and V1 and V2=Velocity (m/s) ∆Z=L=Length of Stroke mm Including the discharge coefficient C = 0.98 to account for viscous effect, ∆P therefore becomes: ∆P= Ï  Q22C2A12A1A22- 1+ LÏ g ∠´ Hydraulic force = Ï  Q22C2A12A1A22- 1+ LÏ gSurface Area of Piston A mm2 = Ï  Q22C2A12A1A22- 1+ LÏ gA2- A1 The forces were algebraically added according the ejection stroke equation developed above (case III) to obtain ?K at different diameter of pistons, fixing inner diameter of Piston D2 (corresponding to A2) = 0.5, 1, 1.5, 2 and 2.5mm (See appendix 3). Force causing motion = Resultant spring force Resultant hydraulic force Frictional force Gravitational force. Mpa= L ∆K- Ï  Q22C2A12A1A22- 1+ LÏ gA2- A1- ÃŽ ¼kMpg- Mpg ∆K= 1LMpa+ ÃŽ ¼kg+g+ Ï  Q22C2A12A1A22- 1+ LÏ gA2- A1 The hydraulic effect is due to the fluid forced out from the suction chamber into the outlet. Therefore the A1 and A2 will be the area of the piston and the outlet, corresponding to diameters D1 and D2 respectively. Also the outlet diameter was assumed to be equal to the inner diameter of the piston. The results obtained for difference in stiffness ?K above, were used to obtain the force from solenoid coil Fs using the injection stroke equation above. Also different diameter of piston were used while varying the inner diameter of piston D2 (corresponding to A2) = 0.5, 1, 1.5, 2 and 2.5mm (See appendix 4). Considering the intake stroke equation for case III: Force causing motion = Force from solenoid Resultant spring force Resultant hydraulic force Frictional force + Gravitational force Mpa= Fs-L∆K- Ï  Q22C2A12A1A22- 1+ LÏ gA1- ÃŽ ¼kMpg+ Mpg Fs= Mpa+ ÃŽ ¼kg-g+L∆K+ Ï  Q22C2A12A1A22- 1+ LÏ g A1 The hydraulic effect is due to the change in pressure as the fluid passes through the piston, because of the reduction in area. Therefore the A1 and A2 will be the area of the piston outer and inner diameter, corresponding to diameters D1 and D2 respectively. B. Pressure Springs: The load analysis of the spring was also done by isolating the spring and analysing the forces acting it. Considering the ejection stroke of upper spring (spring 1), the different forces acting on the spring are as shown below: Force on piston causing acceleration Spring force Resultant hydraulic force (including assumed viscous effect) This is assuming that the frictional force on spring is negligible because the surface area contacting the wall is small. Force causing motion = Spring force + Resultant hydraulic force Mpa= LÃâ€"K1+ Ï  Q22C2A12A1A22- 1+ LÏ g A1 K1=1LMpa- Ï  Q22C2A12A1A22- 1+ LÏ g A1 ∠´K2=K1+∆K Where Force on springs Fsk=KÃâ€"Length of stroke The values of stiffness of springs 1 and 2 were calculated using the relationships above at different outer and inner diameters of the piston. The graphs were plotted to see the variations (See appendix 5 and 6). C. Inlet Valve and Spring: Considering also the inlet valves and analysing the forces acting it, the injection stroke is caused by an increase in volume of the suction chamber, causing a corresponding decrease in pressure. Therefore the different forces acting on the inlet valve are given below: Inlet spring force at compression Resultant hydraulic force (including assumed viscous effect) This is assuming that the frictional force and gravitational force on the valve is negligible because the valve is light. Resultant Pressure Change= ?P From Gas Law: P1V1= P2V2 P1 and P2 are the initial and final pressures of both the inlet and suction chamber respectively (N/mm2). The initial pressure P1 is assumed to be equal to the external pressure which is given to be equal to the atmospheric pressure Pa = 1 bar = 0.1 N/mm2. That is why fluid is not flowing because there is no pressure difference, or P1 was higher than Pa P2= P1V1V2= PaV1V2 where V2=V1+Vs and Vs=Swept Volume per stoke Vs=Flow rateFrequency in stroke/sec=1.667Ãâ€"10490 =185.22 mm2/stroke P2= P1V1V1+Vs ∆P1=Change in pressure due to swept volume= Pa-P2 ∆P1=Pa-PaV1V1+Vs=Pa V1+Vs-PaV1 V1+Vs=PaV1-PaV1+PaVsV1+Vs=PaVsV1+Vs Where V1 = VT and it is the total volume of the inlet spring area, suction chamber and the inner space of the piston. ∆P2=Pressure Change due to area changes ∆P2=Ï  Q22C2A12A1A22- 1+ LÏ g The above pressure change is the sum of the pressure changes from the inlet through suction chamber and into pistons inner diameter. This is negligible because the pressure drops as it enters the suction chamber and increases as it enters the inner diameter of piston, thereby almost cancelling out. ∆P=∆P1=PaVsVT+Vs Hydraulic force=spring force at compression ∆P1A3=PaVsA3VT+Vs= K3x3 PaVs=K3x3A3VT+ K3x3A3Vs VT=PaVs- K3x3A3VsK3x3A3 Where A3=Inlet area mm2, K3=Inlet Spring Stiffness (N/mm) and x3=Spring movement=Valve lifting mm The values the total internal volume VT was obtained at different values of the diameter of the inlet D3 (corresponding to A3). The value of the spring force K3x3 was varied from 0.01 to 0.05 N and the variations were plotted to see an appropriate one (See appendix 7). 2.2 Component Design and Selection The component design has been carried out along with the load analysis shown above. The desired dimensions for different components were then selected after a careful study and analysis of the graphs plotted. The dimensions were selected based on those that satisfy the required specifications, reasonably able to be manufactured and can be selected from the manufacturers catalogue as in the case of the springs2. Below are the component dimensions: Solenoid: Solenoid Frequency: 45cycles/sec = 90 strokes/sec Force from solenoid coil: 108.8N Length of stroke: 7.367 mm Piston: Piston outer diameter: 8 mm Piston inner diameter: 2 mm Springs: Pressure spring 1 rate = 5.771 N/mm Force on spring 1 = Rate * length of stroke = 5.771 * 7.367 = 42.515 N Pressure spring 2 rate = 14.683 N/mm Force on spring 1 = Rate * length of stroke = 14.683 * 7.367 = 108.17 N From the above calculations and estimated values of the spring rates, the most accurate spring chosen from the compression spring catalogue are (see appendix 8 and 9): Spring 1: C6609150 Wire diameter: 1.02 mm Outer Diameter: 7.62 mm Free length: 15.88 mm Rate: 5.81 N/mm Spring 2: D22110 Wire diameter: 1.25 mm Outer Diameter: 7.55mm Free length: 17mm Rate: 15.03 N/mm Inlet: Inlet spring stiffness = 0.02 N/mm Inlet spring length = 9.804 mm Inlet diameter = 1.78 mm 2.3 Stress Analysis The stress analysis was carried out on just two components as shown below. This was because these are the two components whose failure affects the pump operation most. A. Piston: The two stresses acting on the piston are normal and shear stresses which is given as. Stress (N/mm2) sij= Force (N)Area (mm2) The notation is to differentiate between the direction and plane of action, where the first digit represents the plane of action and the second digit represents the direction of force. When the notations are different, it signifies shear stress and when the notations are the same it means normal stress. The force on the piston varies as the piston goes through the cycle, therefore the different forces and principal stresses were calculated as the spring compresses and stretches. This was shown in appendix 10 and 11, but the calculations of the maximum and minimum principal stresses at the springs peak are shown below. The principal stresses were calculated because they are the cause of fracture in a component3. Considering the piston and spring 1: Fig 2.2: Stresses acting on piston from spring 1 and wall3 s11= 0 because there is no horizontal force in that direction s12= Force from SolenoidSurface area of piston= Fsp Do Lp= 108.8pÃâ€"8Ãâ€"15=0.2886 N/mm2 Where D0=Outer diameter of piston mm, Lp=Length of Piston (mm) s22= Force from spring 1Outer Area-Inner Area= K1Lp4 Do2- Di2 s22=5.771 Ãâ€"7.367p4 82- 22= 42.51547.1239=0.9022 N/mm2 s21= 0 because there is no horizontal force in that direction Considering the piston and spring 2: s11= 0 because there is no horizontal force in that direction s12= Force from SolenoidSurface area of piston= Fsp Do Lp= 108.8pÃâ€"8Ãâ€"15=0.2886 N/mm2 Where D0=Outer diameter of piston mm, Lp=Length of Piston (mm) s22= Force from spring 2Outer Area-Inner Area= K2Lp4 Do2- Di2 s22=14.638 Ãâ€"7.367p4 82- 22= 107.838147.1239=2.2884 N/mm2 s21= 0 because there is no horizontal force in that direction The total principal stress which is the usual cause of fracture was calculated using the total normal stresses from the springs and the shear stress from solenoid. Total shear stresses: Ts12=s12 from Spring 1+ s12 from Sprig 2=0.2886+0.2886= 0.5772 Total normal stresses: Ts22=s22 from Spring 1+ s22 from Sprig 2=0.9022+2.2954= 3.1976 Therefore the principal stresses: s11s22- s(s11+s22)+s2-s122=0 0Ãâ€"3.1976- s(0+3.1976)+s2-0.57722=0 s2-3.1976s-0.3331=0 Principal stresses; smin=-0.101 N/mm2, smax=3.2986 N/mm2 B. Pressure Springs: The major stress acting on the spring is shear stress acting on the coils. The force and consequentially the shear stress on the springs vary as the piston deflection (i.e. length of stroke) increases and decreases. The various forces and shear stresses were calculated and the graph plotted (see appendix 12). But the calculation of the maximum shear stress, which occurs at the full deflection is shown below4: Fig 2.4: Force acting on spring4 Shear stress tmax= 8FDWpd3 Where F=Force on spring N D=Mean outer diameter of spring mm d=diameter of spring coil mm W = Wahl Correction Factor which accounts for shear stress resulting from the springs curvature W=4C-14C-4+0.615C C=Dd Considering Spring 1 Fmax= K1Ãâ€"Length of stroke=5.771Ãâ€"7.367=42.515 N/mm2 D=7.62 mm and d=1.02 mm ?C=Dd= 7.621.02=7.4705 W=4C-14C-4+0.615C= 4Ãâ€"7.4705-14Ãâ€"7.4705-4+0.6157.4705=1.1982 tmax= 8FmaxDWpd3= 8Ãâ€"42.515 Ãâ€"7.62Ãâ€"1.1982pÃâ€"1.023=931.113 N/mm2 Considering Spring 2 Fmax= K1Ãâ€"Length of stroke=14.638Ãâ€"7.367=108.17 N/mm2 D=7.55 mm and d=1.25 mm ?C=Dd= 7.551.25=6.04 W=4C-14C-4+0.615C= 4Ãâ€"6.04-14Ãâ€"6.04-4+0.6156.04=1.2506 tmax= 8FmaxDWpd3= 8Ãâ€"108.17 Ãâ€"7.55Ãâ€"1.2506pÃâ€"1.253=1331.119 N/mm2 CHAPTER 3 INITIAL MANUFACTURING DESIGN ANALYSIS 3.1 Dimensions The dimensions of all the main components; piston, springs, cylinder and valves had been obtained from the calculations and graphical analysis made above. However, the detailed dimensions of all components namely; pump body (left and right side), cylinder and liners, piston, springs and valves are shown in the CAD drawing in appendix 13. 3.2 Tolerances Tolerance for Stroke Length The statistical tolerance of the stoke length was calculated using integral method, which is much more effective than an additional tolerance. Given the tolerance of the flow rate as  ± 0.1litres/min, the tolerance of the frequency was assumed to be  ± 5 cycles/sec under normal distribution condition. The tolerance of the stroke length was calculated as follows: Standard deviation s=Tolerance3 Ãâ€"Cp where Cp=process capability index In general manufacturing industry, a process capability index (Cp) of 1.33is considered acceptable. Therefore Cp Flow rateQ=1  ±0.1 lit/min= 1.667 Ãâ€"104  ±1.667 Ãâ€"103mm3/sec   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚     Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   ÏÆ'Q=3.33 Ãâ€"1033 Ãâ€"1.33=8.356 Ãâ€"102 Frequency F= 45  ±5 cycles/sec (Assuming a Normal distributed variable)   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚     Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   ÏÆ'f=103 Ãâ€"1.33=2.506 Therefore the flow rate and frequency could be written as; Q ~ N 1.667 Ãâ€"104 , 8.356 Ãâ€"102 mm3/sec f ~ N 45 , 2.506 cycles/sec Q = Volumetime=Volume Ãâ€"frequency = Ï€ d2 L4 Ãâ€"f ∠´L= 4QÏ€d2f Using differential tolerance: ÏÆ'∅2= i=1n∂∅∂xi2 ÏÆ'xi2 ÏÆ'L2= ∂L∂Q2ÏÆ'Q2+ ∂L∂f2ÏÆ'f2+ ∂L∂d22ÏÆ'd2 ÏÆ'L2= 4Ï€ 1ÃŽ ¼d2 Ãâ€"ÃŽ ¼f2ÏÆ'Q2+ ÃŽ ¼QÃŽ ¼d2 Ãâ€"ÃŽ ¼f22ÏÆ'f2+ ÃŽ ¼QÃŽ ¼d3 Ãâ€"ÃŽ ¼f2ÏÆ'd2 Ãâ€"2 ∠´Tolerance=ÏÆ'3 Ãâ€"Cp The standard deviations and tolerances of the stoke length were calculated using the above equations, while varying the diameter from 1 to 20 mm, and the results were plotted out (see appendix 14). Tolerance for Piston Principal Stress Assuming a normally distributed around the maximum principal stress acting on the piston, the standard deviation and the tolerance of the maximum principal stress was calculated using the load distribution obtained in appendix 11. ∠´3ÏÆ'=3.2918-0.5772=2.7146 Tolerance=CpÃâ€"3ÏÆ'=1.33Ãâ€"2.7146=3.6104 N/mm2 Upper and lower limit=3.61042= ± 1.8052 N/mm2 Tolerance for Springs Shear Stress Also assuming a normally distributed around the maximum shear stress acting on the springs, the standard deviation and the tolerance of the maximum shear stress was calculated using the load distribution obtained in appendix 12. For spring 1: ∠´3ÏÆ'=931.113-0=931.113 Tolerance=CpÃâ€"3ÏÆ'=1.33Ãâ€"931.113=1238.38 N/mm2 Upper and lower limit=1238.382= ± 619.19 N/mm2 For spring 2: ∠´3ÏÆ'=1331.119-0=1331.119 Tolerance=CpÃâ€"3ÏÆ'=1.33Ãâ€"1331.119=1770.39 N/mm2 Upper and lower limit=1770.392= ± 885.195 N/mm2 3.3 Fits The components that are fitted into the cylinder, namely; cylinder liner, piston springs 1 and 2 are almost of equal diameter. But because of the consideration of the fits and limits to give some allowance a transition fit was chosen from â€Å"Data Sheet 4500A British Standard selected ISO Fits-Hole Basis†. Since it fell in between the nominal size of 0 6 mm, the transition fit selected was H700.015 for the hole and k60-0.009 for the shaft5. 3.4 Material Selection Piston and Cylinder The piston and the cylinder are to be made of stainless steel grade 431. This is due to the prevention of fracture which could be caused by principal stress. From the maximum principal stress obtained for the piston above (3.2986 N/mm2 = 3.2986 MPa), it is sure that the material which has a yield strength of 655 MPa will be able to prevent failure. Also the other reason for choosing this material is because of its high resistance to corrosion6. Since the piston and cylinder interacts with the fluid, which increases the tendency for corrosion to occur, it is quite safe to use a highly corrosion resistance material like this. It is also very easily machined in annealed condition. The properties of the stainless steel grade 431are shown in appendix 156. Springs The springs are to be made of stainless steel grade 316. This is also due to the strength of the grade in preventing fracture, breakage and buckling of the spring due to the shear stress acting on it. From the maximum shear stress calculated above (1331.119 N/mm2 = 1.331 GPa), it is sure that this grade of stainless steel with an elastic modulus of 193 GPa will be able to withstand the compression. The material is also highly corrosion resistant and relatively easy to machine. The other properties of the stainless steel grade 316 are shown in appendix 156. Valves The valves are to be made of polytetrafluoroethylene PTFE, which is a thermoplastic. This was chosen because the material has to be light and can easily float. Also, it has very low coefficient of friction, which reduces the fluid drag force and wears on the piston and spring. 3.5 Surface Finish The surface finishing chosen for the manufacturing of the parts was to be 0.8  µm Ra. This is to reduce friction and rate of wear, because there are lots of parts moving against each other. The grinding process requires a very great accuracy because it is a relatively delicate manufacturing process. 3.6 Geometric Tolerance In obtaining the tolerance of the components, since algebraic addition of tolerances is very unrealistic and will not be efficient, the tolerances of components that fit into each other were taken from the â€Å"Data Sheet 4500A British Standard selected ISO Fits-Hole Basis†5. These are show below S/No Parts Dimensions (mm) Tolerances (mm) Drawings 1 Cylinder 11.00 + 0.015 2 Cylinder liner 8.00 0.009 3 Piston 2.00 0.006 4 Spring 1 17.00  ± 0.0015 3.7 Process Selection The manufacturing processes of the various parts of the pump will be very important aspects of the design.The parts to be manufactured are pump body, cylinder liners and piston. It will take a great deal of accuracy in carrying out the process, because the geometry of the parts is very delicate. Any wrong dimension will affect the output or operation of the pump. There are three steps in manufacturing the components mentioned above. Firstly, all the components would be manufactured by casting, which would probably not give the accurate dimensions. Then a turning/boring process can then be carried out, using a CNC or lathe machines, to achieve better dimension. The last process is the surface finish, which gives a smoother and precise dimension. It is relatively easier to manufacture the components by this method because of the intricacies of the geometry and dimensions, and also the materials chosen are easily machined. The manufacturing process of the springs would not be considered in this report because they are provided by suppliers. CHAPTER 4 DESIGN OPTIMISATION 4.1 Component Manufacturing Risk Assessment Component Name Pump Body (Left Right Side) Calculation of qm Drawing number 001 mp = 1 Ãâ€" 1.6 = 1.6 gp = 1.7 Ãâ€" 1 Ãâ€" 1 Ãâ€" 1 Ãâ€" 1.1 Ãâ€" 1.1 = 2.057 Ajustable tol= Design tolmpÃâ€"gp = + 0.0151.6 Ãâ€"2.057=+0.00455 tp = 1.7Ãâ€"1 = 1.7 sp = 1 Ãâ€" 1.3 = 1.3 qm = 1.7 Ãâ€" 1.3 = 2.21 Manufacturing variability risk, qm = 2.21 Material 431 Stainless Steel Manufacturing Process Turning/Boring Characteristic Description Holes at centre to edge Characteristic Dimension 8 mm Design Tolerance + 0.015 Surface Roughness 0.8 µm Ra Component Name Piston Calculation of qm Drawing number 005 mp = 1 Ãâ€" 1.6 = 1.6 gp = 1 Ãâ€" 1 Ãâ€" 1 Ãâ€" 1 Ãâ€" 1 Ãâ€" 1.1 = 1.1 Ajustable tol= Design tolmpÃâ€"gp = 0.0061.6 Ãâ€"1.1=0.0034 tp = 1.7Ãâ€"1 = 1.7 sp = 1 Ãâ€" 1 = 1 qm = 1.7 Ãâ€" 1 = 1.7 Manufacturing variability risk, qm =1.7 Material 431 Stainless Steel Manufacturing Process Turning/Boring Characteristic Description Holes at centre to edge Characteristic Dimension 2 mm Design Tolerance 0.002, -0.008 Surface Roughness 0.8 µm Ra  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   The values of the component manufacturing risk analysis obtained above are considerably with a low risk. This shows that the processes chosen for the manufacturing of the components are acceptable. 4.2 Failure Mode and Effects Analysis (FMEA) The failure mode and effects analysis (FMEA) is an analytical technique performed to ensure that all possible failure modes of the piston pump have being identified and address. Below are the predicted failure modes of each components of the piston pump, the caused, effects and the suggested solutions: It can be seen from the FMEA above that the spring breakage has the greatest severity, but the wear on all the components has the greatest risk priority number. This is because wear would be experience by the customer over time of use which made the risk priority number very high. Therefore, while desig

The Principles of Green Design in Architecture

The Principles of Green Design in Architecture In modern communities, healthy environment is the foundation of our daily lives. However, environmental problems are becoming serious. Much research illustrate that the pollution from architecture, from construction to operation, is one of the main contributors of these problems. The world famous design theorist Victor Papanek claimed in the 1960s, that designers should consider the limited resources around the world to protect the planet. This was the first announcement globally promoting the set of principals of green design. This assignment will firstly explain the principles of green design, then show several applications of these principles and finally evaluate the contribution of these principles to society . According to Yeang and Spector, green design is based on four principles, the green principle, the grey principle, the blue principle and the red principle, which aim to reduce contamination to the environment, recycle waste and reuse energy. The green principle is the principle about interconnecting natural areas and buildings. The grey principle refers to the circular systems in the buildings, such as energy or electric power systems. The blue principle is about the water cycle which should be designed to close the loop, which means that try best to reduce or reuse waste water. Finally, the red principle suggest designers should meet the requirements of customers.When applying these principles in architecture, it means sustainable design to comply with economic, social and ecological sustainability. The green principle states that whenever and wherever possible, the existent natural eco-system should be reserved to a great extent during the period of designing. This has been highlighted by Yeang and Spector (2011), â€Å"having an eco-infrastructure in the master plan is vital†. The obvious benefit, such as providing cleaner air and improving water supply, of designing under the green principle is significant. However, a hidden potential, for instance, being a conditioner of climate change and keeping water from washing away, is also meaningful. As will be illustrated later, designing under green principle bring citizens better lives. The grey principle is the principle which is frequently used in urban engineering. Applying it into architecture aims to regard buildings as a small city. Therefore, buildings should produce parts of energy by themselves, which can lighten the burden of government as numerous pressing global social issues have been caused by limitation of resource. The best explaination of this is the application of solar energy. The third principle of green design is the blue principle, which can also be called the water principle. This principle claims that â€Å"new technological trajectories for the water infrastructure should be applied (Hiessl et al 2001)†. As the predicament of global shortage, it should be used in cyclic way. â€Å"Water used in the built environment needs to be recovered and re-used wherever possible†(Yeang and Spector). As a result, blue principle is an additional built-up principle for green design. The last principle of green design is the red principle, which is a principle of serving human communities directly. Applying this principle, designer should realize what citizens really require, whether they are satisfied with your design. It is important for a designer to remind themselves as a service provider. â€Å"What we do not know can hurt us†(Bondan Sosnowchik, 2007). â€Å"This is the social and human dimension that is often missing in the work of green designers† (Yeang and Spector). As the environmental problems become more and more serious, green design principles have been applied more frequently. Modern buildings always contain element of green design more or less. Designers usually apply principles of green design in their design in order to improve the quality of them. The particular examples below cover the application of the four fundamental principles of green design and demonstrate evidences of the principles of green design that should be used more widely. With the speedy construction, increasing population and rapid-developing transportations, the phenomenon of urban heat island effect become significant, which lead to the environmental deterioration of life quality. Therefore, the applying of green principle require action imperatively. According to this, vertical planting have been utilized in common design. Vertical planting is a technique that uses different resources to allow plants to extend upward rather than grow along the surface of city. In some cases, no support frame of any kind is needed as the plants naturally grows upwards. The plants outside the building provide a layer to protect buildings from sunshine, which is benefit for preserving the temperature inside the buildings. Research demonstrate that buildings with vertical planting would keep the temperature 3-9 degrees lower than without that. With the help of vertical planting, the burden of air- conditioners could reduce 12.7% approximately. It can be seen in some o f modern constructions that green roofs, walls and facades are some of the City of Melbourne’s latest tools in the work to adapt city to climate change. As the rapidly developing of green design, in order to applying the grey principle more effectively, the Building Information Modifying technology, based on the 3D technology, a new building design model collecting and managing effectively all kinds of information in the entire building life circle, have been exploited to assist architects to design recycle systems of buildings(Liu Liu 2013).Applying this new technology, designers could be able to design the circular energy or electric systems inside the buildings, such as solar energy system, to decline the negative effects to environment and to achieve sustainable building design. Furthermore, wind catcher, a suitable ventilation means for houses to creates pleasant airflow in rooms, hall and basement, is another latest technology to reduce the energy of a building requiring to function normally. In addition, while hot water is the largest component of residential energy costs after heating and cooling, a solar domestic water heat ing system that is well designed will provide 50-80% of hot water needs, depending on the building’s geographical location and the time of year. Water, often called the source of life, provides a valuable resource to be celebrated in the process of green design. According to Art Ludwig, only about 6 per cent of water people use for drinking. Consequently, potable water should not use for irrigation or sewage. The Monterey Bay Shores approach to water management is a representative example show how blue principle working. In Monterey Bay Shores’ water systems, main water sources is from the rain, which is collected by a storage and used in swimming pools, toilets, spa, laundry and bath after different processes of treatment. An additional water supplying line is municipal water supply, which provides potable water for drinking and cooking. Finally, all the graywater( used water) after treatments will be irrigated for the plants of green roofs and green walls. Furthermore, the recycling system in Bird’s Nest is another example. With the help of six water collection and storage tanks with a capacity of 12,000 cu m over 70 per cent of the water supply at Bird’s Nest is recycled water, while 23 per cent is recycled rainwater, which will be used for washing the stadium, road, toilet, garage and irrigating the land around the venue. Recent years, residents in modern cities complain more frequently about the crowded sky scrapes. The grim tall buildings bring them the felling of choking. As the quality of people’s lives improved, a place for living is not the basic requirement of customers. The happiness and comfort taken by the style of space have been regard as more important. It tends to be a tendency that applying the red principle in modern design of architecture to satisfied the customers. Bauhaus Design School, the origin of modern design, for some, is synonymous with the greater term modernism. For others, the Bauhaus is a type of font or an architectural design style. â€Å"Architecture is designed for human† is one of the most prominent view of Bauhaus. Architecture is service for people and should be combined with environment to become a gorgeous place for living. In German and Sweden, numerous buildings are designed with large dimensions but amiable, moderate and comfortable. The architec ture to people is what human to nature. While nature never change following the human’s minds, building designers should consider more about the suggests from residents. Otherwise, a eye-attractive design without suitableness for people could not be treat as a successful design. The four principles of green design described above have being applied successfully in many parts of the world and have produced a significant reduction in environmental damage. To be more specific, the mainly benefits of applying principles of green design could be divided into three parts: economic benefits, environmental benefits and social benefits. Firstly, for the economic aspect, green buildings typically have lower annual cost for energy, water, maintenance and other operating expenses. Although the first costs may be higher, the payback would be worthy as the time goes by. Secondly, as original buildings use the energy and produce waste, green buildings could produce energy by themselves and reuse the waste to minimize the pollutant. Furthermore, in social respect, the principles using in green design bring the improvement in the quality of life, health and well-being. Residents in modern community would feel more health, comfortable and satisfactory to live in a green build ing. In conclusion, green design is helpful to relieve the pressing global environmental problems while the situation become increasing serious, such as the urban heat island effect and greenhouse effect. Applying the principles in design, the cost of operating buildings would reduce by a margin, for instance, the expenditure of using air-conditioners will decrease sharply. Furthermore, applying principles of green design could take numerous benefits to people’s health lives. For instance, plants can produce oxygen and absorb carbon dioxide, which suits for human that need oxygen every second particularly. Principles of green design enable people to live in a more comfortable and sustainable environment, which could improve their work efficience and bring them a safer and more environmental friendly future. References Panaek, V 1970, Design for the real world, Sweden. Yeang, K Spector, A(ed) 2011, Green design: from theory to practice, black dog publishing, London, UK. Bondan, P Sosnowchik, K 2007, Sustainable Commercial Interiors, Spain. Henry, Y 2010, An Introduction to Green Building Information Modeling (BIM). http://www.melbourne.vic.gov.au/SUSTAINABILITY/COUNCILACTIONS/Pages/GreenRoofsWallsandFacades.aspx http://bckievning.iweb.bsu.edu/Site/Historical_Movement.html http://www.chinadaily.com.cn/bizchina/2008-05/19/content_6695589_2.htm Hiessl, H, Walz, R Toussaint, D, Design and Sustainability Assessment of Scenarios of Urban Water Infrastructure Systems, ISI, Germany.

Are Looks Worth It? Essay -- Eating Disorders Anorexia Health Essays

Are Looks Worth It? I was recently coming back from Parris Island, SC on a Greyhound bus when I noticed a young girl around my age sitting next to the window across the isle; she looked a lot like me, tall and slim. I did not think anything of it because I have a very fast metabolism and I eat all the time but can not gain weight. Well we stopped to get food and I noticed that she got stuff from McDonalds and was quietly eating her food. About ten minutes after she got done she ran to the back of the bus and into the bathroom. As she was running back there I heard people shouting gwow she just had to smell the food to pukeh, or gthere are way too many anorexic girls now in the world.h As I was hearing those comments I really wanted to stand up for her, but then I just sat there and thought, what do people think of me when I am eating? I have been pegged as an anorexic person my whole life. After awhile it actually starts to sound like a cover up when I tell people, no, I am not anorexic I just have a fast metabolism. A metabolism is all the chemical reactions in the body. When you have a fast metabolism, it is like your body is doing a bunch of exercises with out even moving, so your body burns all the fat; the fat which makes you over weight. People who are overweight and resort to an eating disorder have a hard time loving the person that they really are. There are more people in that Meredith2 situation then you actually think. According to Pirtle, a writer from Health magazine, gAccording to conservative estimates, eating disorders affect between 5 million and 10 million young women in the Untied States. This year, at least 50,000 individuals will die as a direct result of an eating disorder.h In my opinion if socie... ...ersity. 2 Dec 2003 http://search.epnet.com Colino, Stacey. gFreaky New Eating Disorders.h Cosmopolitan 235.6 (Dec 2003): 150 -151 MasterFILE Premier. EBSCO host Camden- Carroll Library Morehead State University. 2 Dec 2003. http://search.epnet.com gNews Briefs: Disordered Eating Attitudes and Behaviors Among Teenage Girls.h Healthy Weight Journal 16.2 (Mar- Apr 2002): 18. FactSearch. Camden- Carroll Library Morehead State University. 2 Dec 2003 OfDea, Jennifer. gThe New Self- Esteem Approach for the Prevention of Body Image and Eating Problems in Children and Adolescents.h Healthy Weight Journal. 16.6 (Nov- Dec. 2002): 89-93 Fact Search. Camden- Carroll Library Morehead State University. 2 Dec 2003 Pirtle, Jennifer. gMind: eWhy Donft They Just Eat?f.h Health 16.2 (Mar. 2002): 96+. Fact Search. Camden-Carroll Library Morehead State University. 2 Dec 2003.

social engineering Essay -- essays research papers

Pedophilia in short is the desire of an adult for sexual contact with children. Pedophiles have been known to molest children only hours after being released from a lengthy prison sentence. In some instances, they kill their victims in order to cover up their crimes. Over the years, society has implemented many attempts to contain pedophilia including such measures as incarceration, therapy, and even castration. Few of these have proven successful. Pedophilia poses an alarming problem for society, particularly the children who are the victims of the sexual abuse. According to Bertrand (2005) â€Å"In the United States, up to 500,000 cases are reported each year, and many more go unreported. In 1990, this crime cost over $2 billion -- and this figure does not include psychotherapy for the child... social engineering Essay -- essays research papers Pedophilia in short is the desire of an adult for sexual contact with children. Pedophiles have been known to molest children only hours after being released from a lengthy prison sentence. In some instances, they kill their victims in order to cover up their crimes. Over the years, society has implemented many attempts to contain pedophilia including such measures as incarceration, therapy, and even castration. Few of these have proven successful. Pedophilia poses an alarming problem for society, particularly the children who are the victims of the sexual abuse. According to Bertrand (2005) â€Å"In the United States, up to 500,000 cases are reported each year, and many more go unreported. In 1990, this crime cost over $2 billion -- and this figure does not include psychotherapy for the child...

Cisco Systems Inc Implementing ERP Essay

Cisco was far away the biggest software vendor customer supporting the application that supported order entry, manufacturing and financial. Cisco wanted to grow from $500 million to $5 billion plus company, but the application was not proving the degree of maintainability, reliability and redundancy are needed. Moreover, Cisco was not able to make the needed changes to the application anymore to meet their business needed because it was too customized (n.a 146). Difficulties in system replacement of the functional areas further perpetuated deterioration of the legacy environment of Cisco. Moreover, system outages were a routine, and this was exacerbated by product shortcomings that made it difficult to recover from the outages. Finally, the legacy environment of Cisco dramatically failed in January 1994 that it was hard to ignore the shortcomings of their existing systems leading to shut down for two days. The struggle, to recover by Cisco from the shutdown, made the managers of Cisc o conclude that there was a need for an alternative approach, hence the decision to deploy ERP system (n.a 147). What are the main reasons for Cisco to select Oracle as an ERP vendor? Before selecting Oracle as an ERP vendor, Cisco and KPMG went to the software market to identify the best packages of software. They oriented their process of selection to what people were actually using and in two days narrowed down to five packages. After evaluating the packages for a week, the team settled on two candidates, another major player in the market of ERP and oracle. The decision was also based on the fact that the vendors were not to be significantly smaller than Cisco. Finally cisco settled on oracle because of numerous factors (n.a 148). Cisco’s project was strongly being driven by manufacturing and Oracle has a better capability of manufacturing compared to other vendors (n.a 148-149). Oracle also had many promises concerning the long term package functionality development. Moreover, Oracle was flexible and was close by in addition to a belief that Oracle was highly motivated to the success of the project (n.a 149). How did Cisco form its ERP implementation team? In forming the ERP implementation team, Cisco sought the very best to include in the project from its core of 20 to about 100, to represent a cross section of the business community of Cisco. Recruitment to the team was for a short term duration and not a career change to the selected candidates. Cisco also extended relationship with KPMG because of the firm’s performance through the selection process of the software and its continued commitment to provide seasoned personnel to the project (n.a 151 para 2). The Cisco’s team members were placed into five â€Å"process area teams† (tracks) with each track comprising of Cisco business leader, Cisco information systems leader, IT and Business consultants from either Oracle or KPMG, and other personnel as team members from the business (para 3). The management of the tracks was being done from the office of the project management which comprised of KPMG project manager Mark Lee, and Tom Herbert, Cisco’s business project manager. Sitting on top of the whole structure of project management was the Executive Steering Committee which included VP of customer advocacy, VP of manufacturing, Corporate Controller, Partner in charge of the KPMG’s West Coast Consulting, and Oracles senior VP of Applications (para 4). References Pearson Custom Business Resources. New York: Pearson Learning Solutions, 2010. Print. Source document

The Structural Frame for Merck & Co., Inc.

In 1994, Merck & Co., Inc. hired Ray Gilmore as chief operating officer to help survive the turmoil of the pharmaceutic industry. Gilmore followed a structural frame capitalise on the strong technical custom of Merck & Co., Inc. who attained a powerful scientific engine.While Vagelos acted as CEO, Merck maintained a strong structure frame through with(predicate) and through the domination of the smart sets senior Research and suppuration (R&D) scientists with strong support from ships caller CEO. When Gilmartin became Mercks CEO, he replaced the two exe ejective vice chairwoman positions with a larger Management charge (MC). MC was directed to mitigate the companys credit line processes to build cross- operational skills rather than restructure company organization. Gilmartin expressed his structural frame through the redefinition of employees roles and relations to rid the company of its utilitarian and divisional barriers.Gilmartins structural face could in like manner b e seen in his creation of ecumenic Business Strategy Teams (WBSTs) to expand idiosyncratic managers idea, cooking and actions beyond existing usable areas. The teams were composed of members from all different practicable divisions of the company.Gilmartins structural frame activities improved Mercks planning and resource allocation through cross-functional product line processes.The Human Resource Frame for Merck & Co., Inc.The human being resource frame is evident in Merck tradition of high ethical standards since many another(prenominal) of the company employees had a high aspire to save lives. The company CEO proclaimed We try neer to forget that medicate is for the people. It is not the profits. The profits follow, and if we take a leak remembered that, they never failed to appear.1 The company also maintained a cultural image in check with its academic image. confederacy scientists and clinicians were addressed as Doctor.Gilmartin created his symbolic frame by interviewing employees crossways the company about their views on major issues set about Merck. He cleared the perplexity and ambiguity concerning the lack of strategic thinking and clear vision. He further raise employee communication by the initiation of a comprehensive internal review of the issues facing the company by interviewing 800 employees across Mercks functional areas.Gilmartin activities of human resource created a very positive view of Mercks strategy among company employees. One manager said We have a clear direction now. Employees make much progress on circumspection and leadership development.Stakeholders of rofecoxibA total of stakeholders were involved in the Vioxx medicate recalling incident of Merck & Co., Inc. in 2004. Internal stakeholders were Merck & Co., Inc. Company employees and Merck & Co., Inc. company shareholders. External stakeholders were the patients who took the medicine, and the United States health Department.Negative Impact of the re call of the Vioxx drug to StockholdersThe Merck & Co., Inc. stock was considered dead currency in 2004 in expectation to the occur of lawsuits filed against the company over safety concerns of the drug. If Merck & Co., Inc. loses the cases, it faces a potentially huge cost from the reimbursements to patients as well as payments for ongoing medical examination monitoring of people who took Vioxx.The recalling of Vioxx caused an yearbook decrease income of $2.5 billion. Following the of the announcement of the recall, investors dumped Merck & Co., Inc. shares do a 30% decrease to come home the lowest closing price in more than eight years. The recall would cut the $1.52 annual dividend and shave at least 50 cents a share, or 16%, off the $3.14 share analysts expected the company to earn in 2004.Recommendation to ebb the Recall of VioxxMerck & Co., Inc. should seek the takings and marketing of innovative products to increase its gross revenue in response to the decrease caused by the recall of Vioxx. In an attempt to improve its public image and ethical stance, Merck & Co., Inc. should keep some of its senior trouble who baron have been responsible for production of Vioxx. The at bottom punishment of its own top management would convince the public of the commitment to higher ethical standards. 1 George W. Merck, the son of the companys U.S. founder quoted in Merck Sharp & Dohame, A brief history, Merck & Co., Inc,. 1992, p. 18.