Search results

Although the increasing performance of microprocessor is developing very fast, the temperature at the junction of an electronic package (chip temperature) has become the limiting factor that determines the lifetime of the microprocessor.
The motherboard thickness is 0.015cm and thickness of chips is 0.3cm each, both made from epoxy molding compound (EMC). 52.5cm Outlet Wind Tunnel 33.3cm 3cm 8cm 10cm Inlet 1 2 3 4 9cm a) Four PLCC Outlet 52.5cm 33.3cm 5 6 7 8 3cm 8cm 10cm Inlet 1 2 3 4 Wind Tunnel 9cm b) Eight PLCC 9 cm 7 cm 10 cm Mother Board (PCB) c) Front view Fig. 1 : Simulation setup for 4 and 8 PLCC packages Table 1 : Dimension of components used in simulation Component Quantity Size(cm3) Wind tunnel 1 52.5x10x10 Motherboard 1 33.3x0.15x8 Chip 4,8 2x0.3x2 A combined model is used for packages and the properties of the packages are uniform.
It is tolerable as slight difference in shape may not affect the simulation result.
Kuat, CFD application in Electronics System Cooling, Final Year Project, School of Mechanical Engineering, Universiti Sains Malaysia, 1998
[23] B.Jayakumar, G.A Quadir, M.Z.Abdullah and K.N.Setharamu, Three Dimensional CFD Conjugate Analysis Of Two Inline PLCC Packages Horizontally Mounted, School Of Mechanical Engineering, Universiti Sains Malaysia, 2002

Schilling1 1 Karlsruhe Institute of Technology, Institute for Applied Geosciences, Kaiserstr. 12, 76131 Karlsruhe, Germany 2 Frank Laboratory of Neutron Physics, JINR Dubna, 141980 Dubna, Russia 3 Institute of Geosciences, University of Kiel, Otto-Hahn-Platz 1, 24098 Kiel, Germany 4 Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany a christian.scheffzuek@kit.edu Keywords: gneiss, Western Alps, neutron-TOF-diffraction, crystallographic preferred orientation, residual strain, applied strain, Rietveld analysis Abstract Two polyphase gneiss samples (Western Alps, Switzerland) consisting of quartz, albite, muscovite and microcline have been investigated with respect to anisotropic physical properties - residual and applied strain - and crystallographic preferred orientations.
As CPO evaluation was the task, useful parameters to be refined in the MAUD, apart from orientation distributions (which were fitted using a discrete EWIMV algorith9m [8] with 5° resolution in the orientation space) and phase volume fractions, were the crystal lattice parameters, the single isotropic temperature factor Biso for all the atoms in the sample, and peak shape parameters (isotropic microstrain and crystallite size).
In contrast, the quartz CPOs of samples Go1 and Go2 are very similar and, therefore, not affected by the folding.
It is also possible that micropores associated with mica platelets (e.g. [12]) are able to accommodate applied mechanical stress to some degree.
Additionally, the relatively large grain size of quartz (100 µm) in relation to the investigated gauge volume of 2 cm3 may affect the observed strain magnitudes.

In these models, the influence of the permeability of rock on the fracture propagation is assumed to be practically negligible. 2 We employed the Flow-coupled Rock Failure Process Analysis code (F-RFPA 2D ); The results indicate that both the rock heterogeneity and the permeability affect the fracture initiation and propagation significantly, and that the simplistic premise that rock is homogeneous and impermeable may apply to limited, but not general cases in hydraulic fracturing. 2.
The mechanical parameters, such as Young's modulus, the strength, and the permeability coefficient, etc., of the elements are all randomly assigned following a Weibull's distribution law to account for the inherent variabilities in rock property [11].
The homogeneity indices m=1.5 denote parameters of distribution, The mechanical parameters of the rock samples are shown in Table1 Table1 Mechanics Parameters Mechanics Parameters value Loading fashion value homogeneity index ( m) 1.5, 2, 3, 6, 20 residual intensity coefficient ( 'λ=f cr/ fc = f tr/ ft ) 0.2 Young's modulus (E / MPa) 33800 the coefficent of pore-water pressure (α) 0.1 internal friction angle ( ϕ /°) 30 permeability coefficient (K/ m/d) 0.001 compressive strength( f c/ MPa) 220 mutation coefficient of permeability (ξ ) 20 ratio of tensile and compressive ( f c/ ft ) 10 Coupling coefficient (β) 0.05 Poisson's ratio (­) 0.25 3.
Therefore, the location and orientation of the fracture initiation is unpredictable. 3.2 Hydraulic fracture path As we know, the analysis of hydraulic fracture is plagued by the question of the validity of conventional fracture parameters such as critical stress intensity factor.

Alwarsamy2, b 1&2Department of Mechanical Engineering, 1Sri Chandrasekharendra Saraswathi Viswa Maha Vidyalaya University, Enathur, Kancheepuram – 631561, Tamil Nadu, India, 2 Government College of Technology, Coimbatore-13 Tamil Nadu, India, aprabhu.9495@gmail.com, btalwarsamy@gmail.com.
The quality of the weld clad bead geometry is achieved by controlling the process parameters through developing the mathematical model and predicting the significant factors.
The cladding process enhances the base material properties.
I*S+0.017778*I*N+0.012667*S*N-0.00103*I2-0.00062*S2-0.07641*N2 (3) Height of reinforcement mm= -17.196-0.1654*I+0.227714*S+1.669368*N+5E-05*I*S-0.00306*I*N-0.01717*S*N+0.000521*I2+0.000223*S2+0.06078*N2 (4) Depth of penetration mm= -24.3134+0.124903*I+0.044042*S+0.869707*N+1.67E-05*I*S-0.0015*I*N-0.00139*S*N-0.00021*I2-6.6E-05*S2-0.00734*N2 (5) Dilution %= +1340.245-9.0031*I-1.11156*S-21.8489*N-0.00256*I*S+0.027278*I*N+0.127833*S*N+0.02105*I2-0.00233*S2-0.27719*N2 (6) Table 3 Anova for models developed Bead geometry Sum of squares Degrees of freedom Mean square F-ratio R2 Adj R2 AP Reg Res Reg Res Reg Res BW 10.39 0.46 9 10 1.15 0.046 24.85 0.96 0.92 15.34 HR 2.22 0.086 9 10 0.25 0.0085 28.80 0.96 0.92 18.09 DP 0.27 0.0036 9 10 0.029 0.00036 81.77 0.99 0.97 30.43 DL 572.03 10.86 9 10 63.56 1.09 58.51 0.98 0.96 29.82 Checking the Adequacy of the Model Developed The objective of ANOVA is to validate the process parameter significance that affects

Recent experiments [1] showed that adding Mn to an Fe-Cu alloy leads to a notable slowing down of coarsening process, that is, to a sharp increasing of density and reducing the sizes of precipitates, which improves the mechanical properties and hinders embrittlement [2, 4].
For the large g2 ≫ 1 used, the cut-off factor Fc(k) is reduced to the gaussian exp (−k2l2/2) with lc = ga where a is the lattice constant.
Because of that, relaxation times for the main alloy component distributions are by a factor 1/cvi slower than the times of relaxation of vacancies at the given {cpi} to their ``quasi-equilibrium'' distribution cvi{cpi}.
The resulting effective mobilities are similar to Eq. (10) but the factor Bij is replaced by some other averages allowing for the configurational dependences of γpv [11].
At the same time, for the given s, lowering temperature affects microstructure more strongly than increasing concentration.

Fig.1 Plane view of the overall structure Fig.2 Schematic map of the truss string structure Calculation and Finite element modeling With the help of the finite element program Midas/Gen [7], three models were established to discuss how the construction processes affect the established structure.
A model including all the parts was firstly built, then the established elements of current construction stage were endowed with real property, at the same time the stiffness of the elements unestablished was set to zero until all the elements were established [9].
The structural state can be divided into three configurations: the zero state, the initial state and the loading state according to the process, construction and mechanical characteristics of truss string structures.
(4) The construction method of projects should be taken into account simultaneously of all factors mentioned in this paper and any other cases such as the cost and the period of construction.

Introduction Soil is a quite complex material with stress-strain behaviors affected by many and various factors, which show significant differences in mechanical characteristics under different loading paths and different gravity stress conditions.
Via centrifugal shakers, the dynamic property and the failure mechanism of soil mass and geotechnical structures can be truly reproduced by exerting dynamic loads of sine waves and seismic waves on models while the same gravity stress as prototype is produced.

To control and prevent the cracking of steel it is necessary to understand the chemical and physical properties of hydrogen inside BCC iron.
The adequacy of the theoretical framework and the different convergence thresholds has been tested by computing a number of known properties for clean -iron.
Indeed, important changes in the elastic properties of iron are found in these regions.
DQ is only lower than the thermal one, DT, by a factor of 6.
The residual or mechanical stresses change the diffusion barrier.

Hence, there are still difficulties to be solved in applying MQL to the cutting of difficult-to-machine materials, which cause severe tool damages resulting in short tool service life due to their material properties of high strength, low thermal conductivity, high affinity to cutting tools, high strain hardening, etc [4].
Hence the better surface finish in MQL cutting must be attributed to the good lubricating properties of the ester though only a small amount of the ester is supplied to the cutting point.
This suggests that the lubricating property of oil mist, which should affect the tool life favorably, was cancelled by some negative effects owing to the high flow rate of the compressed air.
This suggests that the lubricating property of oil mist was cancelled by the negative effect of the high flow rate of the air.
Hence, the pressure of air supply is the major controlling factor of MQL cutting as far as the finish-turning of Inconel 718 is concerned.

Hexavalent chromium has been widely used for surface coating due to its extraordinary properties such as good wear and corrosion resistance, high hardness, low coefficient and so on.
Moreover, organic additives played an important roles in enhancement of surface characteristics such as levelling, brightness, anticorrosion, and packing factor [2-4, 8].
In the present work, the effect of addition PEG on the coatings structure, surface morphology, roughness and mechanical properties such as hardness and corrosion resistance have been investigated.
The addition of PEG does not affect the deposition of Cr and C in this case.
Chuang, Role of nickel undercoat and reduction-flame heating on the mechanical properties of Cr-C deposit electroplated from a trivalent chromium based bath, Surf.