bluuebunny/crossref_metadata_2025 huggingface dataset:
Flexible Electrode Structures for Thermo-Tunneling Applications
Authors: Enikov Eniko T. , Gamez Carlos , Kanjiyani Shezaan , Ganji Mahdi , Gill Joshua
Published: August 2012

Combined thermionic emission and tunneling of hot electrons (thermo-tunneling) has emerged as a potential new solid-state cooling technology. Practical implementation of thermo-tunneling, however, requires the formation of a nanometer-sized gap spanning macroscopically significant surfaces. Thermo-tunneling of hot electrons across a few-nanometer gap has application to vacuum electronics, flat panel displays, and holds great potential in thermo-electric cooling and energy generation. Development of new thermo-tunneling applications requires creation of a stable nanometer gap between two surfaces. This presentation is focused on our effort to investigate the feasibility of creating such gaps using distributed electro-magnetic forces arising in thin-film flexible structures. Early efforts based on rigid electrodes showed that the effective tunneling approaches 400 square-micrometers, which albeit small, could lead to useful practical systems. In this presentation, we report a theoretical and experimental investigation of a thin-electrode system which could lead to further increase on the effective tunneling area. The device under study consists of a thin membrane collector electrode (anode) suspended over the emitting electrode (cathode). The structure is placed in a vacuum enclosure with an externally generated magnetic field perpendicular to the current flow in the membrane. The resulting Lorentz force is then directed upwards, separating the two surfaces. A mathematical model of the steady-state operation of the device is presented along with predictions of the contact area and tunneling current. Essential output parameters of the model include a central contact area measured by its length (delta) and the thermo-tunneling current. Both parameters are determined as a function of the externally applied external potential and magnetic field. Numerical solutions of the model show two possible operating modes: (1) symmetric deformation with negligibly small current; and (2) asymmetric mode where the B-field controls the current and contact area.
Optimization of Positive Pressure Ventiliation Tactic for Wind Driven High Rise Fires
Authors: Panindre Prabodh , Kumar Sunil , Narendranath Atulya , Manjunath Vinay Kanive , Chintaluri Venkata Pushkar , Prajapati Vishal
Published: August 2012

Positive Pressure Ventilation (PPV) is a firefighting tactic that can mitigate the spread of fire and the combustion products to improve the safety of firefighters and civilians in wind-driven high-rise fires than without PPV. The performance of a PPV tactic in wind-driven high-rise fires depends on various parameters that include wind speed, control of stairwell doors, number of fans, fan positions and placements, fire location etc. This paper describes the influence of these parameters on the efficacy of PPV operation that was studied by simulating wind-driven high-rise fire scenarios using computational fluid dynamics softwares Fluent 12.0 and NIST’s Fire dynamic simulator (FDS 5.0). The results obtained from Fluent and FDS found to be in close agreement with each other and have been used to optimize the PPV operation for better performance.
Study of Cells Attachment Using Impedance Spectroscopy Technique
Authors: Nordin Anis N. , Arifuzzaman S. M. , Mel Maizirwan , Spray David , Voiculescu Ioana
Published: August 2012

In this paper we report on the electrical impedance spectroscopy characterization of the attachment of two mammalian cell lines: endothelial cells (RFPEC) and fibroblast cells (V79). For electrical cell–substrate impedance sensing (ECIS) of the endothelial cells a commercially available eight-well cell culture impedance array (ECIS-8W1E) was used. The impedance measurements were recorded with cell culture medium (without cells) and with endothelial cells or fibroblast cells in the culture medium over a frequency range from 100 Hz to 100 kHz. The impedance measurements were compared to the equivalent circuit model. The impedance measurements were also simulated using COMSOL Multiphysics™, a commercially available modeling package.
Nanoparticle Deposition and Convective Transport in Microchannel Heat Exchanger Systems
Authors: Coleman Joshua P. , Nnanna A. G. Agwu
Published: August 2012

In the absence of dispersants, surfactants or other deposition inhibiting techniques, nanoparticles contained in a base fluid could potentially deposit on channel walls. Nanoparticle layering has been shown to impact heat transfer coefficient, alter hydrodynamic characteristics including viscosity and flow regime, and influence the onset of boundary layers. The rate of deposition is a function of nanoparticle size, heat flux, microchannel hydraulic diameter, fluid velocity, temperature, adhesion properties and volume fraction. This paper presents an analytical investigation of nanoparticle deposition in microchannel heat exchanger systems. The objective of this study is to correlate the rate of deposition with nanoparticle size, microchannel hydraulic diameter, heat flux and volume fraction for transient flow conditions in which Brownian diffusion and thermophoresis are appreciable slip mechanisms of nanoparticle transport. A two-component four-equation nonhomogeneous thermal equilibrium model for mass, momentum and energy in nanofluids that includes nanoparticle mass transport into the channel walls is used in this analysis. An analytical model representing the transient distribution of nanoparticles in a channel is proposed.
Effects of High Shear Rate on Thrombus Formation Process on Pipe Orifice Flows
Authors: Tamagawa Masaaki
Published: August 2012

This paper describes visualization of thrombus formation process on orifice flows by laser sheet beam. The aim is to investigate the effects of high shear stress or shear rate on the thrombus formation or thrombus formation rate. In addition, the experimental results are compared with the CFD results. As a result, it was found that the high shear rate region of the flow has large effects of the thrombus formation and prediction method based on CFD can be used.
Life Prediction Model Development of BGA Solder Joint Under Random Vibration
Authors: Han Changwoon , Oh Chul-Min , Hong Won-Sik
Published: August 2012

Automotive industry faces social demands of advancing the performance and efficiency, which leads to the increasing development and adoption of vehicle electronic instrument. The properties of the Ball Grid Array (BGA) packages such as smaller size and higher I/O counts make them attractive for the automotive electronics application. The application of the BGA package raises doubts for the reliability in automotive harsh environment. Vibration environment originated from the engine or outside of a vehicle is one of the detrimental stress factors for the electronic instrument [1].
Suspended Decoupler Design of Hydraulic Engine Mount
Authors: Jazar Reza N. , Mahinfalah M. , Christopherson J.
Published: August 2012

A known problem in classical hydraulic engine mount is that because of the density mismatch between the decoupler and surrounding fluid, the decoupler might float, or stick to the cage bounds, assuming static conditions. The problem appears in the transient response of a bottomed up floating decoupler hydraulic engine mount. To overcome the bottomed up problem, a suspended decoupler design for improved decoupler control is introduced. The new design does not noticeably effect the mechanisms steady state behavior, but improves start up and transient response. Additionally, the decoupler mechanism is incorporated into a smaller, lighter, yet more tunable and hence more effective hydraulic mount design. Ususally the elastomechanical components in a hydraulic engine mount are assumed lumped and linear. To have a more realistic modeling, utilizing nonlinear finite elements in conjunction with a lumped parameter modeling approach, we evaluate the resorting characteristics of the components and implement them in the equations of motion. The steady state response of a dimensionless model of the mount is examined utilizing the averaging perturbation method applied to a set of second order nonlinear ordinary differential equations. It is shown that the frequency responses of the floating and suspended decoupled designs are similar and functional.
Simulation of Post Failure Response in Fiber Composites
Authors: Veluri Badrinath , Myhre Jensen Henrik
Published: August 2012

This study focuses on the compressive failure mechanism in the form of kinkband formation in fiber composites. Taking into account the non-linearities of the constituents, a constitutive model for unidirectional layered materials has been developed and incorporated as a user material in a commercially available finite element code to study effects of kinkband inclination angle and micro-geometry on kinkband formation. The localization of deformation into a single kinkband is studied. In the post failure regime a state is reached where deformation in the kinkband gets stabilized and the kinkband broadens under steady-state conditions.
Application of Viscoelastic Fluids in Industrial Dampers
Authors: Ashrafi Nariman , Eskafi Mohamad Reza
Published: August 2012

A nonlinear viscoelastic damper is designed for several industrial applications. The damper is structurally similar to typical commercial dampers and the design is based on the choice of the viscoelastic material used as damping agent in the damper. Given the rheological parameters of certain material known from experiments, the coefficients of Johnson-Segalman constitutive equation model for the material are evaluated by fitting the data. The problem is first formulated by writing the governing equations for the flow between two parallel flat plates, i.e. Couette flow. The velocity and stress are represented by symmetric and antisymmetric Chandrasekhar functions in space. Both inertia and normal stress effects are included. A numerical scheme is applied to solve the governing equations in time domain projected by Galerkin method. For given Reynolds number and viscosity ratio, two critical Weissenberg numbers are found at which an exchange of stability occurs between the Couette and other steady flows. The model is capable of predicting the nonlinear amplitude-dependent behavior of viscoelastic dampers under single and multiple-frequency excitations.
Optimization and Comparison of Direct and Indirect Supercritical Carbon Dioxide Power Plant Cycles for Nuclear Applications
Authors: Harvego Edwin A. , McKellar Michael G.
Published: August 2012

Results of analyses performed using the UniSim process analyses software to evaluate the performance of both a direct and indirect supercritical CO2 Brayton power plant cycle with recompression at different reactor outlet temperatures are presented. The direct supercritical CO2 power plant cycle transferred heat directly from a 600 MWt reactor to the supercritical CO2 working fluid supplied to the turbine generator at approximately 20 MPa. The indirect supercritical CO2 cycle assumed a helium-cooled Very High Temperature Reactor (VHTR), operating at a primary system pressure of approximately 7.0 MPa, delivered heat through an intermediate heat exchanger to the secondary indirect supercritical CO2 recompression Brayton cycle, again operating at a pressure of about 20 MPa. For both the direct and indirect power plant cycles, sensitivity calculations were performed for reactor outlet temperature between 550°C and 850°C. The UniSim models used realistic component parameters and operating conditions to model the complete reactor and power conversion systems. CO2 properties were evaluated, and the operating ranges of the cycles were adjusted to take advantage of the rapidly changing properties of CO2 near the critical point. The results of the analyses showed that, for the direct supercritical CO2 power plant cycle, thermal efficiencies in the range of approximately 40 to 50% can be achieved over the reactor coolant outlet temperature range of 550°C to 850°C. For the indirect supercritical CO2 power plant cycle, thermal efficiencies were approximately 11–13% lower than those obtained for the direct cycle over the same reactor outlet temperature range.
Simulation of Stress-Fracture in Human Vertebral Body due to Extreme Weight Lifting
Authors: Ranu Harcharan Singh , Bhullar Aman Sweet
Published: August 2012

Lumbar vertebrae are a heavily loaded component of human body. They are subjected to repetitive loading in daily activities. However, limited information on failure mechanism of lumbar vertebrae are available to date. Thus, the need to develop an analytical model to predict stress-fracture characteristics of vertebral body. A linear elastic fracture mechanics approach has been considered and a mathematical model has been proposed so that the predictions can be made more easily related to the occurrence of injury. Study reveals that for a person weighing 1334 N and lifting a weight of 345 kg during squat exercise causes a vertebral stress-fracture at 12 repetitive standing lifting. While same load at lowest position yields a stress-fracture at less than 3 lifting. Numerical study shows that for change of position from standing to lowest position resultant compressive force acting on spine increases by two times whereas the possibility of stress-fracture increases by five times. Similarly at dead lift exercise, lifting 325 kg from standing to lowest position increases resultant compressive forces on vertebrae by 2.5 times. However, stress-fracture ratio increases by six times. Study reveals that for a person weighing 800 N (height = 1.8 m) and lifting a weight of 900 N, vertebrae can be subjected to stress-fracture by three cyclic lifting. Rate of injury is dependent on flexion angle i.e. as flexion angle increases, so does rate of injury.
Closed Form Solutions for the Statical Behavior of Micromirrors Under Capillary Forces
Authors: Moeenfard Hamid , Darvishian Ali , Ahmadian Mohammad Taghi
Published: August 2012

In this paper, the static behavior of micromirrors under the effect of capillary forces is studied. First the equation governing the static behavior of micromirrors is obtained using both Newton method and minimum potential energy principle. Then energy method is employed to investigate the static instability of micromirrors equilibrium points. It is proved that when there exist two equilibrium points, the smaller one is stable and the larger one is unstable. Furthermore a design equation is suggested for the successful fabrication process of micromirrors in the stable operatives range. Then the statical behavior of micromirrors is investigated numerically and analytically using the Homotopy Perturbation Method (HPM). It is observed that with increasing the instability number defined in the paper, the rotation angle of the micromirror is increased and suddenly the pull-in occurs. The analytical results well follow the numerical ones and so the presented analytical method can be used for a fast and accurate design tool for micromirrors fabrication.
Optimized Design of Single Link Flexible Manipulator
Authors: Mahto S. , Dixit U. S.
Published: August 2012

In this work, size optimization of a single link flexible robotic manipulator is carried out by considering the link as an Euler-Bernoulli beam. Finite element method is used for obtaining the natural frequencies and time response. Sequential quadratic programming method is used to maximize fundamental frequencies of the manipulator for different designs. A comparative study of the optimized designs is carried out to find out their suitability for real world situation. Based on the numerical experimentation, suggestion for formulating optimization problem for varying tip loads is provided.
Development of Compact Thermal-Fluid Models at the Electronic Equipment Level
Authors: Stafford Jason , Grimes Ronan , Newport David
Published: August 2012

The introduction of compact thermal models (CTM) into CFD codes has significantly reduced computational requirements when representing complex, multi-layered, and orthotropic heat generating electronic components in the design of electronic equipment. This study develops a novel procedure for generating compact thermal-fluid models (CTFM) of electronic equipment that are independent over a boundary condition set. This boundary condition set is estimated based on the information received at the preliminary design stages of a product. In this procedure, CFD has been used to generate a detailed model of the electronic equipment, and a commercially available thermal network analyzer has been implemented to produce the CTFM and optimize an objective function to minimize discrepancies between detailed and compact solutions. It was determined that CTFM nodal temperatures could predict the corresponding area averaged temperatures from the detailed CFD model to within 6% (Celsius scale) over the intended boundary condition range. Results also highlight the necessity to subdivide the compact thermal model into the largest possible isothermal nodal elements to retain the useful features of the CTFM. The approach presented has the potential to reduce CFD requirements for multi-scale electronic systems, such as in the design of aircraft avionics bays, and also has the ability to integrate experimental data in the latter product design stages.
High-Accuracy Location Estimation Method Using Public Wireless Networks Based on Radio Intensity Prediction for Logistics Tracking Terminal
Authors: Yokoi N. , Hosaka H. , Sakata K.
Published: August 2012

For higher positioning accuracy of the low-power-consumption tracking terminal specific to the physical distribution management, a positioning technique using the Personal Handy-phone System (PHS) was developed.
Combined Effect of Isoproterenol and Mechanical Oscillation on the Contractile Response of Mice Airway Smooth Muscle
Authors: Jo-Avila M. J. , Al-Jumaily A. M. , Mbikou P. , Sobrevia L.
Published: August 2012

An asthmatic attack is instigated by hyperconstriction of airway smooth muscle (ASM). This can be relieved with bronchodilator medication such as Isoproterenol (ISO). This paper hypothesizes that mechanical oscillations may improve drugs therapy when combined with ISO. Preliminary results indicate that combining ISO with breathing equivalent mechanical oscillations trends to increase the relaxation response as compared with the use of ISO alone. The effect of superposed oscillations in the range of 10–30 Hz of frequency applied over breathing equivalent mechanical oscillations was also assessed in the study.
Water for Biomass-Based Energy on Maui, Hawaii
Authors: Grubert Emily , King Carey W. , Webber Michael E.
Published: August 2012

Biomass-based energy has characteristics that could help Maui Island meet multiple long-term goals, including decreasing reliance on oil for electricity and transportation fuels, increasing use of local resources that do not need to be shipped long distances, and diversifying the island economy beyond tourism by preserving agriculture. Biomass can be used for liquid fuel production and for electricity production. On Maui, sugarcane has been grown at plantation scale for over a century. Accordingly, sugarcane-derived ethanol and combustible sugarcane bagasse have long been of interest as energy sources for the island. State and county level focus on increasing renewable energy utilization on Maui have renewed study of potential crops and available land, with a special emphasis on sugarcane. However, there is some concern about the water requirements associated with biomass-based energy. A primary motivation for using local, renewable energy sources is that Maui is an island with limited resources, fresh water among them: thus, exploring ways to increase energy sustainability without compromising water availability is of interest to many. This work examines the water needs associated with growing sugarcane for ethanol and combustible biomass on Maui Island. Virtually all sugarcane on Maui is irrigated because soil and sunlight resources do not generally coincide with natural precipitation patterns. Growing sugarcane for energy represents a large water demand that is limiting under certain development scenarios on Maui, such as a scenario where environmental streamflows are highly prioritized. By comparing the irrigation demand of Maui’s currently grown sugarcane with published figures for ethanol yield from cane, this work finds that 700 to 1,500 gallons (gal) of irrigation water are needed per gallon of sugarcane-based ethanol (from fermentable sugars and fiber; 0.7 to 1.5 cubic meters, m3, per liter, L). More water is needed for processing. However, combustible waste streams could provide additional energy return per unit of water. This paper discusses how water demand for sugarcane-based energy interacts with other island water demands, given that about 37,000 acres (150 km2) of sugarcane land are potentially available for bioenergy production. Though seawater cannot be successfully directly used for irrigation, sugarcane can tolerate some salinity and other contamination, so this paper also considers brackish water and treated wastewater — for which there is little other demand — as potential irrigation resources. Notably, the range of tolerable water quality expands significantly when sugarcane is not intended for human ingestion or when biomass yield, not sugar content, is targeted (as for cellulosic ethanol or combustible biomass production).
Optimal Central Composite Design for Manufacturing Simulation of 0.50 Caliber Projectile
Authors: Echempati Raghu , Ane Bernadetta Kwintiana , Krueger Mark E. , Roller Dieter
Published: August 2012

Design and manufacturing simulations of critical components such as bullets are considered crucial, particularly, when it is associated with the expense and time constraint of the engineering projects. During the manufacturing, the projectile jacket is the component that faces the greatest strain or stress. In order to find an optimal manufacturing operation for the .50 caliber projectile, an experiment is performed using the Box-Wilson Central Composite Design (CCD) using a combination of two controlled factors, i.e., friction coefficients and hardening exponents, with three-levels of each. The sensitivity of the plastic strain to the hardening exponent and friction coefficients is analyzed. The response surface plot fits well to the second-order polynomial function and is able to provide relative the same plots when the model is extended up to the fourth-order. Furthermore, it is found that the greatest plasticity likely to occur in the jacket walls as the ironing process is performed. Based on the residual strain and stresses analysis, it is evident that the selected material used in the production of projectile is viable. Finally, the ductile fracture analysis confirms that the jacket design is considered safe for the selected manufacturing processes.
Study of Factors in Coffee-Ring Structure Formation Using PIV Methods
Authors: Han Kewen , Zhang Zhe , Wereley Steven T. , Oh Je Hoon
Published: August 2012

The evaporating liquid droplet with suspended particles on a solid substrate may leave a ring-like structure along the droplet circumference under certain conditions, which is commonly known as the coffee ring phenomenon. This phenomenon has many interesting applications related to microfluidic problem such as self-assembly of colloidal particle, particle and biomolecule separation and concentration and ink-jet printing. Although much work has been done on this topic, not very much work focused on the fluid flow inside a droplet. In order to investigate the inner flow inside of the droplet, water solutions with the fluorescing or non-fluorescing particles as the solute are dropped on surfaces with different hydrophilicity. The whole process are recorded using high dynamic CCD camera system and analyzed using Particle Image Velocimetry (PIV) methods. It is found that in all the droplets that form coffee ring, a central symmetric outward radial flow is observed. The velocity of the flow is zero at the center of the droplet. Along with radius outside, the flow velocity increases. For the same droplet, the flow velocity increases as the evaporation goes on and the velocity reaches its maximum at the end the evaporation. For different droplets, with the higher concentration, smaller droplet size and more hydrophilic surface, the flow velocity is larger. Comparisons between the experimental data and the published convection models show that the flow can be considered as part of the flow caused by the maximum evaporation rate at the pinned wetting line.
Numerical Evaluation of Energy Absorption of Crashworthy Structure for Railway’s Rolling Stock: Application of Damage Mechanics Model
Authors: Kimura Souta , Mochida Toshihiko , Kawasaki Takeshi , Nakamura Hideyuki , Yamaguchi Takashi
Published: August 2012

The energy absorption of a crashworthy structure for railway’s rolling stock was studied experimentally and numerically. A quasi-static compression test was conducted using a full-scale mockup of a crashworthy structure constructed with welded aluminum alloys. To predict the experimental results, a finite element (FE) simulation was conducted in which the Gurson-Tvergaard-Needleman (GTN) model, representing the accumulation of ductile fractures by the nucleation, growth and coalescence of micro-voids, was employed as the constitutive equations of the parent aluminum alloys and welded regions. A simulation employing the Von-Mises yielding model as the constitutive equations was performed as a conventional approach to demonstrate the advantages of the simulation using the GTN model in predicting the energy absorbing ability. The predictions of the GTN model simulation were proved to be in better agreement with the experimental data than those of the simulation based on the Von-Mises model. The relationship between the total energy absorption and the local phenomena observed in the compression test is discussed.
Global Sensitivity Analysis of Solder Joint Fatigue Life Model
Authors: Wu Mei-Ling
Published: August 2012

This paper focuses on global model uncertainty analysis, that is, how the input data uncertainty (global model data) affects the output data (solder joint fatigue life cycle). From the output data issue, how do we estimate uncertainty for each result (solder joint fatigue life cycle)? Assume the model structure is corrected, how do we estimate a physics of failure (PoF) and predict time to failure or cycle to failure? Identifying an approach for quantifying the combination of input and uncertainty would enable the determination of more realistic confidence limits on Physics of Failure (PoF) predictions. The goal of this present work is how some uncertainty might affect the prediction outcome. The effect of prediction model used and the calculation approach is also studied in this work.
Evaluation of Parts of a Boat Cabin Based on Exergy: Focusing on Environmental and Economic Assessments
Authors: Medyna Galina , Coatane´a Eric , Millet Dominique
Published: August 2012

Product and process engineering design is a complex problem which relies on multiple fields, and while many design aid tools exist they rarely take into account more than a single field or aspect at a time. This implies that a few tools have to used for a single project, making the engineer, or designer, juggle among them or favouring a single aspect. Many existing environmental assessment tools on the market only focus on environmental aspects, which are extremely important in today’s impact conscious context but are not enough to make viable products and processes. Moreover the tools often require precise data which is only known during the late stages of design when it is too late to make any significant changes. The aim of the current work is to further develop and test a multi-domain modelling framework, for the early stages of product and process design, which primarily focuses on environmental assessment but also takes into account economic aspects and can be expanded to further fields, such as risk. The two bases for the proposed framework are exergy, a measure of useful work that can be, unlike energy, both created and destroyed, and dimensional analysis, a widely used tool in engineering to model problems through dimensional homogeneity. The environmental and economic assessments proposed by the tool are illustrated on the case of insulation of the cabin on a passenger ferry and the environmental results are compared to those from two existing methodologies, Eco-Indicator and Cumulative Exergy Demand.
Carbon Footprint Calculator for Construction Projects
Authors: Ammouri Ali H. , Srour Issam , Hamade Ramsey F.
Published: August 2012

With the advent of awareness regarding carbon emissions and desirable reduction, this paper provides a calculator for the estimation of carbon footprint resulting from construction projects. For this purpose, we developed a software toolkit dubbed ‘Carbon Footprint Calculator for Construction Projects (CFCCP)’ capable of building a complete construction material database of carbon emissions. This is accomplished by accounting for wide range variables including construction size, landscape, and material construction. This calculator yields more accurate estimates as compared with other recently introduced calculators which consider only the general inputs of a certain project and produce estimates within ±25% accuracy. In this paper, the cost of the accuracy is accomplished via quality library variables such as project design plan, detailed bill of quantities (BOQ), and schedule timeline. The tool automatically outputs a detailed report describing the tasks and their associated carbon emissions which enables managers to take corrective measures to minimize these emissions before the onset of the project. Although the focus of this paper is on construction projects, the utilization of CFCCP may also be extended to other project types if database files for the project material can be built. For example, potential applications may involve the design of green buildings given that these kinds of buildings typically utilize materials from distant sources resulting in noticeable increase in their initial carbon footprint.
Evaluating the Carbon Embedded in the US Public Water Supply
Authors: Twomey Kelly M. , Webber Michael E.
Published: August 2012

The United States uses approximately 5% of its primary energy and 6% of its electricity to pump, convey, treat, distribute, heat, and recondition water in the US public water supply. Allocating this energy towards water has contributed to a national public water distribution system that is considered among the best in the world, providing its users with a clean and reliable water supply. This water supply, treated to stringent water standards defined by the Environmental Protection Agency’s Safe Drinking Water Act, has been critical to the health and livelihood of United States’ citizens. However, this energy-expenditure comes at an environmental cost, since the majority of water-related energy is derived from burning fossil fuels. Fossil-fuel combustion emits carbon-dioxide, a greenhouse gas that has become of concern in recent years because of its connection to anthropogenic climate change. The amount of carbon-dioxide that is emitted from fossil-fuel combustion is principally a function of the quantity and type of fuel that is burned for energy. This first-order analysis quantifying national water-related carbon dioxide emissions is the second in a series of several analyses by the authors, quantifying the energy and greenhouse emissions embedded in the US public water supply. Results indicate that water withdrawal, conveyance, treatment, distribution, end-use preparation, and wastewater treatment produces approximately 301 million metric tonnes of CO2 emissions annually. This quantity is 5.1% of total US CO2 emissions in 2009, which is approximately equal to emissions from the gasoline consumed by one-quarter of the US passenger fleet in the same year. Considering that the emissions associated with water for industrial, municipal and self-supplied sectors (such as agriculture) were not included in this analysis, the actual quantity of carbon emissions released as a result of water-related activities is likely to be higher. Consequently, identifying efficiency measures and conservation schemes to reduce the amount of water-related energy consumed in the US might be significant in achieving future greenhouse gas emission reduction goals.
Test Environment for an Elastic Mechanism—Related to a Kirchhoff Plate—for Usage as Pressure Sensor
Authors: Ottnad T. , Irlinger F. , Lueth T. C.
Published: August 2012

Control of pressure is a decisive factor in many technical applications as pump control, injection moulding, press control, and many more. Issues as high plant safety and high process reliability require suitable methods of monitoring and control of pressure. The large range of applications with specific technical framework conditions result in many different solutions for specific tasks. Pressure switches come to action when control of minimum required pressure or maximum pressure are desired. Combination of both leads to complete control of pressure which is an important influencing factor in plastics processing. Giving the example of injection moulding importance of the control of pressure is obvious. To guarantee proper injection scales especially in toolmouldings with high complexity it can be necessary to use several pressure sensors simultaneously. Having found the final geometry of the injection system and having determined the locations where the pressure is of high interest, proven and tested pressure sensors are the best choice. Finding those locations can be elaborate and means extensive effort while testing. Common state-of-the-art pressure sensors most often transform mechanical deformation into electrical signals and these in turn are converted into the value of pressure. Separate pressure chambers might be necessary, often the pressure range is limited, and usage of electrical components lead to constraints concerning temperature range. Using a flexible element and determining the pressure by its deformation eliminates thermal insulation and electromagnetic shielding. Keeping such a flexible element as simple as possible can result in a thin plate with a ram on its outer side to measure its deflection. To convert deflection into pressure it is necessary to know the stiffness of the flexible element. Regarding the flexible element as Kirchhoff plate with a constant bending stiffness implies linear dependency between working pressure and resulting deflection theoretically. This interrelationship is aimed for because it simplifies conversion significantly. To proof this dependency practically a test rig was constructed. As substitution of the pressure a variable but defined load can be applied. Furthermore the test rig can be heated and can be used as test bench for durability analysis. Measurements with different plates show the expected linear dependency within the measurement range which means constant stiffness.
Scale Effect on Boiling Inception and Bubble Dynamics in Micro/Mini/Macro Tubes
Authors: Wu Di , Piao Ying , Duan Yuan-yuan , Yang Zhen
Published: August 2012

The present study experimentally and theoretically investigated the scale effect on boiling inception and following liquid-vapor interfacial evolution in horizontal tubes with inner diameter varying from 0.05 mm to 3.0 mm. Reducing scale, i.e., decreasing tube inner diameter, significantly increases the critical heat flux of bubble nucleation. A novel thermodynamic model and derived q″w,c–Tw curve were used to explore the scale effect on bubble nucleation and corresponding mechanisms. It is concluded that reducing scale remarkably enhances heat transfer performance close to the heated wall and increases temperature gradient of liquid, which consequently suppresses boiling inception and increases the critical heat flux. Diverse interfacial movement behaviors were found, by which tubes were classified into various scales as, micro scale (Di ≤ 200 μm) with explosive emission boiling, mini scale (200 μm < Di < 2.5 mm) with distinct spherical and following oblate bubble growth stages and macro scale (Di ≥ 2.5 mm) with spherical bubble growth stage only. Interaction between liquid-vapor interfacial movement and thin film evaporation, induced by the reduced scale, was considered to be the crucial factor to bring about phenomena of explosive emission boiling in micro tube and spherical-to-oblate bubble growth in mini tube which are quite different from that in macro tube. Different models were developed to describe the diverse liquid-vapor interfacial movement behaviors, which provides insight into the scale effect on interfacial movements.
Risk Assessment Overview
Authors: Prassinos Peter G. , Lyver John W. , Bui Chinh T.
Published: August 2012

Risk assessment is used in many industries to identify and manage risks. Initially developed for use on aeronautical and nuclear systems, risk assessment has been applied to transportation, chemical, computer, financial, and security systems among others. It is used to gain an understanding of the weaknesses or vulnerabilities in a system so modification can be made to increase operability, efficiency, and safety and to reduce failure and down-time. Risk assessment results are primary inputs to risk-informed decision making; where risk information including uncertainty is used along with other pertinent information to assist management in the decision-making process. Therefore, to be useful, a risk assessment must be directed at specific objectives. As the world embraces the globalization of trade and manufacturing, understanding the associated risk become important to decision making. Applying risk assessment techniques to a global system of development, manufacturing, and transportation can provide insight into how the system can fail, the likelihood of system failure and the consequences of system failure. The risk assessment can identify those elements that contribute most to risk and identify measures to prevent and mitigate failures, disruptions, and damaging outcomes. In addition, risk associated with public and environment impact can be identified. The risk insights gained can be applied to making decisions concerning suitable development and manufacturing locations, supply chains, and transportation strategies. While risk assessment has been mostly applied to mechanical and electrical systems, the concepts and techniques can be applied across other systems and activities. This paper provides a basic overview of the development of a risk assessment.
Extra- and Intracellular Ice Formation of Attached Caski Cells Under Directional Cooling
Authors: Li Yuhui , Wang Hao
Published: August 2012

Intracellular ice formation (IIF) is of great importance in cryobiology but its mechanisms are still under debate. In this work a micro-layer chip with a sandwiched thin layer of medium was employed to facilitate the observation of IIF; and thermoelectric chips were used to induce a directional cooling along the chip. Remarkable phenomena of extracellular ice formation (EIF) triggering IIF were observed. The extracellular ice contacted and “penetrated through” and initiated the intracellular ice. In the aid of the fluorescent reagents, it was found that the cell membrane could keep intact even though the cell had undergone IIF, and the intact cell could have IIF again in the next freezing cycle, until the membrane was finally ruptured. The results shed light on the IIF mechanisms.
Simulation of Red Blood Cell Deformation in Microvessels Using a New Rapid Modified Particle Method
Authors: Firoozbakhsh K. , Ahmadian M. T. , Hasanian M. , Samiezadeh S.
Published: August 2012

The deformation of human red blood cell has been a topic of considerable scientific interest and real-life significance. Several methods have been improved to simulate the behavior of red blood cells motion and deformation in micro-capillaries. Since in microscopic scales, using discrete models are more preferred than continuum methods, moving particle semi-implicit method (MPS) which is one of the recent innovative particle based methods, can simulate micro-fluidic flows based on Navier-Stocks equations. It has been shown that original MPS method has a lack of rapid calculation which leads to massive calculations and long time simulation. Quite a few studies have been done to improve MPS method. But the main problem, calculation of viscosity effect in conjunction with fluid pressure distribution, is still under discussion. In this paper a new algorithm is proposed that is to say by this method simulation duration decreases by the factor of 20 while the accuracy of the results remains constant. The results indicate that while the velocity precision is as well as original method, the duration of simulation is reduced more than 20 times. This significant novel MPS algorithm can be implemented in future studies for simulation of multi-fluid flows, complex geometry flows and micro-scale biomedical phenomena.
MEMS-Based Phase Change for Heat Transfer With Thermoelectric Devices and Energy Harvesting
Authors: Ogbonnaya E. , Jakub-Wood B. , Champagne C. , Chukwu S. , Weiss L.
Published: August 2012

The investigation of a capillary-based heat exchanger is presented for potential integration with thermoelectric devices and thermal energy harvesting. The exchanger is a microfabricated device, designed to promote phase change of low boiling-point working fluids and enhance heat transfer from thermoelectric devices as a result. Several heat exchanger designs are studied and compared in these experiments. All designs rely on capillary channels to pump working fluid from surrounding reservoirs out across a heated exchanger surface. First, a baseline silicon device is fabricated using standard RIE techniques to produce silicon capillary channels. Channel widths of 100 μm are studied with varying heights. In addition to this base silicon device, SU-8 is used to further vary channel height. Heat exchangers are characterized based on operating temperature and heat input using 3M™ HFE 7200 working fluid. Maximum mass transfer rate recorded is 5.50 mg/s for Si channels operating above the boiling point of the working fluid. By contrast, SU-8 channels are shown to be more effective at temperatures below the boiling point. Maximum mass transfer rate is 2.29 mg/s for SU-8 based channels operating at these reduced temperatures.
Combustion Properties of Spray Flames of Canola Methyl Ester and Diesel Blends
Authors: Aldana Cristian , Parthasarathy Ramkumar N. , Gollahalli Subramanyam R.
Published: August 2012

Canola methyl ester (CME) is a biofuel that is produced by the transesterification of canola oil; it is renewable, carbon-neutral and low in sulfur content. The objective of this study was to document the combustion characteristics of spray flames of CME and No 2 diesel (petroleum fuel) blends. Three blends with 25%, 50% and 75% volume concentration of CME were studied. The fuel was atomized and mixed with air in a heated environment at a supply equivalence ratio of 0.62. Measurements of global CO and NO emissions, inflame temperature and in-flame concentrations of combustion products were made. The near-injector homogeneous gas-phase reaction zone increased in size with the addition of CME. The global CO and NO emissions decreased with the increase in CME content in the fuel blend. The in-flame NO concentration profiles and flame temperature profiles followed similar trends, suggesting that the thermal mechanism of NO formation was dominant in these flames.
A Comparison of the Discrete Ordinates Method and Finite Volume Method for Radiative Heat Transfer Analysis
Authors: Hunter Brian , Huai Xiulan , Guo Zhixiong
Published: August 2012

The time-dependent equation of radiative transfer is solved for a participating medium housed in an axisymmetric cylindrical enclosure by both the discrete-ordinates method and the finite volume method. Many heat transfer processes, including absorption of renewable and sustainable solar energy in a solar receiving tube for use in power plants, can be modeled in a cylindrical enclosure. Steady-state and transient heat flux profiles are generated for both purely absorbing and absorbing-scattering media using both solution methods. The effect of changes in scattering albedo and optical thickness is investigated. A basic modeling of a solar energy receiving tube is presented, and the volumetric radiative absorbed energy rate at the radial centerline is calculated to determine the amount of absorbed energy that can be transferred to a working fluid in a solar reactor. Comparisons of both computational time and committed memory usage for each method are presented. In general, heat fluxes predicted by the FVM with 288 directions tend to slightly underpredict those determined using the DOM S16 quadrature. The FVM requires more committed memory and has longer convergence times than the DOM due to the inherent differences in angular quadrature.
Ensuring Reliability in Lean New Product Development
Authors: Paschkewitz John J.
Published: August 2012

Many companies have begun their lean journey. This typically begins on the shop floor with lean manufacturing methods. This soon leads to applying lean to other processes including new product development. Lean New Product Development (Lean NPD) creates value and eliminates waste by creating knowledge up front to enable informed design decisions and eliminate rework loops. From a quality and reliability perspective, this should be viewed positively because it offers the opportunity to do what is needed up front to ensure robust and reliable products. This paper provides an introduction to Lean NPD and shows how it can be applied to reliability needs definition, design decisions, risk assessment and mitigation, critical characteristics and process control, product testing, failure analysis and corrective action to improve product reliability and robustness. Lean product development changes the focus of how design and development are done, and reliability and robustness tasks are part of the up front knowledge development that facilitates better decisions to get the product right the first time and eliminate the waste of rework and repeated development loops.
Maskless Photolithography Using an Epifluorescent Microscope for Microfluidic Applications
Authors: Higgins MacCallister , Geiger Emil J.
Published: August 2012

We present a technique for fabricating molds suitable for casting PDMS based microfluidic devices using equipment readily available to most microfluidic researchers, namely an epi-fluorescent microscope. By focusing the UV light emitted from the Hg arc lamp, we demonstrate the ability to direct-write photoresist features with a minimum resolution of 45 μm. A major advantage of this technique is its low-cost, both in terms of capital investment and on-going expenditures. Furthermore, by using a motorized stage, we can quickly fabricate a design on demand, eliminating the need, cost, and time required for a photomask. We demonstrate this technique using dry-film resist, due to its low-cost, ease of application, and less stringent safety protocols. In the future, we plan to expand our efforts to higher resolution photoresists such as SU-8.