The fuel transmission is a complex system and involved many of equipment and devices so; it can obtain big economical benefits from building the system model and optimizing the parameters of each element in the system. For engineering, the model construction and its’ solving needs fast and robust. This paper presents a way to construct the optimum model based on the present worth of uniform series of amount (PWUSA) method. Combing the each cost in the system, the objective function, Ctotal = ∑Ci, is build up. The relationship of system parameters has been approached by using thermo dynamics. As a typical example, the paper gives the detail calculating procedure of minimizing cost for the design of a gas pipeline which recovers the work on destination. The results show that direct calculation with MATH CAD software is a fast and practical way to solve practical engineering problem and design. The parameter optimization can minimize the cost of the whole system.

With increasing concerns over terrorist threats, it is imperative to evaluate the effects of fires in tunnels that are commonly used in the mass transit systems. In recent years, predictions and simulations of fire hazard and smoke movements have become common with availability of fast and affordable computers and development of better physical models for use in simulation software.

This paper deals with the dynamics of pool fire in a ventilated tunnel using Computational Fluid Dynamics (CFD) software, CFX 5.6 by Ansys Inc. The main goals of the paper are 1) to analyze the effectiveness of ventilation system in reducing the fire hazards, 2) to trace the movements of harmful gases like carbon monoxide and carbon dioxide, 3) to assess and validate the results of simulation with literature experimental data.

The geometry of tunnel was based on the tunnel size used in the experiments by Fletcher, Kent, Apte and Green in the paper “Numerical Simulations of Smoke Movement from a Pool Fire in a Ventilated Tunnel”. Turbulence, radiation, and combustion models were included in the simulations. A gaseous fuel, methane, and liquid fuels, butane and propane were considered in the simulations. For each fuel, different values of air velocity and their effects on the fire dynamics were evaluated. Simulations were conducted for a variety of ventilation conditions. The simulations were able to predict height and shape of fire, traces of carbon dioxide, carbon monoxide and nitrogen oxide gases, temperature distributions in tunnel, and heat fluxes on the walls of the tunnel.

Work pieces with spherical type features present intense challenge to the machine geometry capabilities where a continuous circular style pattern is constantly being implemented. Verification of machine tool path error estimation is based on important observations that may well be explained through the utilization of Laser Interferometry and Ball Bar testing. Characterization of Mazak Quickturn 20 slant bed lathe was carried out at Southern University to evaluate the machine’s capability for manufacturing hemispherical parts. An error budget assessment of machine tool was performed to support an estimate of quality of machined parts. The estimate of P-V (peak to value) form error for 1-inch diameter hemispherical shape was 0.0018-inch.The estimated diameter for 1-inch diameter hemispherical shape was 1.0022-inch. The estimated P-V form error for 4-inch diameter hemispherical shape was 0.0030-inch. The estimated diameter for 4-inch diameter was 3.9989-inch. Based on these estimates recommendations were made for the machine tool path error compensation.

The performance of gas turbines can be increased in two ways: one by reducing the air requirement for the cooling of the turbine blades, second one by increasing the operating temperature of the turbine blades. Taking into account the later approach the blade material must withstand high temperatures of about 1350˚C. For this enhancing purpose protective coatings called the thermal barrier coatings (TBC) are being employed. The thermal barrier coating mainly consists of two layers; one is the metallic coating MCrAlY which is the premiere layer over the substrate Ni based supper alloy. And the other one is the ceramic layer made of ZrO₂ +7% wt Yttria. Apart from these two layers, an intermediate layer called Al₂O₃ is formed by the oxidation of the aluminum in MCrAlY called as diffusion layer which also enhances the adhesion between the two layers. The present study is an investigation on the insitu thermal variation of TBCs by varying the number of coating layers and simultaneously increasing the operating temperature. The above thermal boundary value problem is modeled and solved numerically using a commercial computational fluid dynamics and heat transfer software. Two samples of Ni based supper alloy substrate with dimensions 40 X 40 X 3 mm are considered; one sample with single layer coating of ZrO₂ +7% wt Yttria and the other one with five coating layers of ZrO₂ +7% wt Yttria for transient thermal analysis. Transient temperature histories will be presented for the use in a thermo-mechanical analysis in order to predict the failure modes in the TBC.

A new thermodynamic approach for sublimation inside of elastoplastic material is developed. Utilizing continuum thermodynamics, a driving force for sublimation, X, is derived. The problem of nucleation of a spherical gas bulb inside the spherical elastoplastic material is solved analytically. The thermodynamically equilibrium relationship between pressure and temperature were obtained from the condition X=0. Activation energy Q was also calculated. The relationship between sublimation pressure and temperature was obtained from the condition Q=80 kT, where k is the Boltzman constant and T is the temperature. Both the kinetic and thermodynamically equilibrium relationship between sublimation pressure and temperature were compared with those for sublimation from external surface (pressure is constant) and sublimation in rigid solid (volume is constant). Results are specified for sublimation in HMX energetic material.

The Ginzburg-Landau equation is used to describe a wide class of first order phase transformations (PTs), which includes ferroelastic, martensitic, reconstructive, ferroelectric and magnetoelastic PTs, PTs in liquid crystals, twinning and dislocation generation. For one-dimensional spatial variation of the order parameter, various types of static analytical solutions were found.  To study the stability of stationary solutions, both analytical and numerical methods were employed.  For nanofilms, solution represents some continuously varied phases with continuously varied properties, which we called functionally graded nanophases. Our results suggest a way to produce such nanophases by dissolving material of nanofilm from both surfaces. An analytical solution for a diffuse propagating interface is found and its stability is studied.

A new continuum approach to martensite crystallography is developed for temperature and stress-induced martensitic transformations. A representative volume is considered consisting of austenite (A) and twinned martensite (M) divided by a plane interface. The assumption of homogeneous stress and strain fields in A and each M variant is adopted. Plastic slip along slip systems of A and M is taken into account. The stresses and strains in A and each M variant are described by algebraic equations. All crystallographic parameters are described by thermodynamically consistent kinetic equations, as well as by slip rules.  Competition between slip and twinning as an accommodation mechanism is studied. Our approach significantly generalizes the crystallographic theory of M. A computational algorithm is developed and numerical study of bcc-fcc stress-induced transformation in steel is performed.

A three-phase system with structural changes (SC) 1«2, 1«3 and 2«3 was studied. A simple strain-controlled kinetic equations for strain-induced phase transformations and chemical reactions are thermodynamically derived. It considers the possibility of direct and reverse SCs and the difference in plastic strain in each phase due to the different yield stress of the phases. A stationary solution for these equations is found and analyzed. Stationary solution explains zero pressure hysteresis observed experimentally as well as the appearance of new phases, especially strong phases, which were not obtained without shear. Also an explanation was obtained why a nonreacting matrix with a yield stress higher (lower) than that for reagents significantly accelerates (slows down) the reactions.

Current engineering design practices and procedures assume vertical-bore heat exchangers (VBHEx) are located within homogeneous material and only account for conduction heat transfer.  An improvement would include the addition of convection heat transfer due to the existence of groundwater flows within the borefield.  The authors have recently developed one such means via an effective thermal conductivity correlation that can be used in traditional VBHEx design models, resulting in a combined (conduction and convection) borehole design length.  Primary parameters include the dimensionless Peclet number and porosity.  This paper discusses the usefulness of the same effective thermal conductivity correlation for VBHEx within layered geologies, containing both confined aquifers and layers without groundwater flow. 

Three measures of discrepancy (Star, Centered L2, and Wrap-Around L2) are evaluated for use in the distributed hypercube-sampling scheme.  The desired discrepancy measure must be sensitive enough to avoid clusters and voids on the hypercube as well as “streaking” that can occur on higher dimensional faces of the hypercube.  In addition to the discrepancy measure’s sensitivity, it must be modifiable in order to incorporate weighted “faces” and the ability to incrementally increase the sample size efficiently and restart as needed.  Of the three measures evaluated, the Wrap-Around L2 discrepancy measure stood out based on its ability to be modified to suit the needs of the distributed hypercube-sampling scheme and its sensitivity to detect clusters and voids.

The short coming of failure of natural air to dry agricultural food products to levels of safe storage and processing is surmounted by the use of a heated air food dehydrator (dryer). The heated air drying system absorbs more moisture from food products than the natural air drying system and hence dries the food faster. Experiments were carried out on potatoes. Heated air was made to flow through a layer of potatoes by a fan. The drying air was heated by an electrical heater. The air heater unit was made up of ply wood and trays made from a galvanized mesh wire. Air flow of air through the system was provided by a fan capable of moving at least 0.25 m3/sec.m2 of air. The chamber was placed on a concrete surface where other processing equipment was installed. The ambient, inlet and outlet temperatures and velocities were recorded respectively. The temperatures for ten other locations in dryer unit were recorded. Air velocity, moisture content and pressure difference at different points were also recorded.
The objectives of this research were as follows.
Model the variation of heat loss within grain layer thickness.
Model heat loss along the drier wall.
Model the variation of heat loss along a fixed layer of grain in a drier.
Model mass transfer within the drying layer.
The drying temperature and air flow rate were varied, for fixed food layer thickness, one at a time. To achieve the above objectives, the analysis involved setting up and solving energy and mass balances equations as follows.
Energy equations, for the air and the product
Mass equations, for the air and the product

This paper discusses the changes in material properties and in optical response resulting from femtosecond laser processing of lithium niobate crystals. A variable energy Ti-Sapphire laser system was used to machine lithium niobate on the surface and subsurface. The end state was then studied using electron and ion microscopy techniques. It is observed that several processes like ablation, partial redeposition and thermal shock and extreme quenching occur during the processing, resulting in both amorphization and heavily defective regions. Post-machining, optical reading (planar illumination) of the surface and sub-surface structures facilitated the selective readout of these structures of sizes as small as 2 m. A relation between the size and shape of these spots, the energy used to write them and their optical response is observed. Such understanding is important in achieving better spatial, structural, chemical and hence optical resolution for scaling up in 3-D optical memory and related light-guiding applications.