bluuebunny/crossref_metadata_2025 huggingface dataset:
Pulsed Heat Transfer for Thermal Maximum Power Point Tracking
Authors: McKay Ian Salmon , Wang Evelyn N.
Published: April 2014

This paper presents a new method for enhancing thermal energy harvesting via pulsed heat transfer. By acting as a variable thermal resistance that theoretically generates no entropy, a pulsed thermal connection allows calibration of the effective thermal resistance of an energy harvesting system. By adjusting the frequency and duty cycle of the pulsed heat transfer, the method allows an energy harvester to be continuously optimized for a variable incident heat flux. In this paper, the analysis of a generalized model shows how the pulse strategy theoretically allows any heat engine-heat sink pair to work at the same power and efficiency as a 1:1 thermal resistance-matched engine-heat sink pair of equal or greater total thermal resistance. Experiments with a mechanical thermal switch validate this model, and show how the pulse strategy can improve the efficiency of a system with equal engine and heat sink thermal resistances by over 80% with no increase in the hot-side maximum temperature, although at reduced total power. At a 1:2 engine-sink resistance ratio, the improvement can simultaneously exceed 60% in power and 15% in efficiency. The thermal pulse strategy could be implemented to improve of a variety of systems that convert thermal energy, from waste heat harvesters to the radioisotope power systems on many spacecraft.
Combustion Characteristics of Spray Flames of Canola Methyl Ester/Diesel Blends in a Furnace
Authors: Morton Cory D. , Tran Victor H. , Parthasarathy Ramkumar N. , Gollahalli Subramanyam R.
Published: April 2014

The combustion characteristics of spray flames of canola methyl ester (CME) and blends with diesel fuel within a re-radiating environment were studied. The combustion chamber was lined with refractory bricks that were preheated to about 725 K (1305 °R). The flow rates of the fuels provided a constant heat release rate of about 7.33 kW (25,000 BTU/hr) at atmospheric pressure. Measurements of flame temperature, in-flame concentrations, global emissions, flame radiation and soot volume fraction were taken. The global CO emission index was significantly lower in the biofuel blend spray flames compared to that of the diesel spray flame. The global NO emission index was comparable for all spray flames, which agreed with peak flame temperature and in-flame NO concentration measurements. The radiative fraction of heat release was also comparable for all spray flames.
Exploring Lithium-Ion Intensity and Distribution via a Time-of-Flight Secondary Ion Mass Spectroscopy
Authors: ChiuHuang Cheng-Kai , Zhou Chuanzhen , Huang Hsiao-Ying Shadow
Published: April 2014

For high rate-capability and low cost lithium-ion batteries, the prevention of capacity loss is one of major challenges facing by lithium-ion batteries today. During electrochemical processes, lithium ions diffuse from and insert into battery electrodes accompanied with the phase transformation, where ionic diffusivity and concentration are keys to the resultant battery capacity. In the current study, we first compare voltage vs. capacity curves at different C-rates (1C, 2C, 6C, 10C). Second, lithium-ion distributions and intensity are quantified via the Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS). The result shows that voltage vs. capacity relations are C-rate dependent and larger hystereses are observed in the higher C-rate samples. Detailed quantification of lithium-ion intensity for the 1C sample is conducted. It is observed that lithium-ions are distributed uniformly inside the electrode. Therefore, the current study provides a qualitative and quantitative data to better understand C-rate dependent phenomenon of LiFePO4 battery cells.
Verification, Validation and Uncertainty Quantification of a Nuclear Thermal Hydraulics Code
Authors: Aydogan Fatih
Published: April 2014

Nuclear thermal hydraulics codes are used in designing next generation systems and analyzing existing designs. Since most of the nuclear safety analyses employ nuclear thermal hydraulics codes, every step of the development in these codes are carefully verified and validated (V&V). This study shows the V&V steps of uncertainty equations implemented into the nuclear safety code of Coolant Boiling in Rod Arrays Code-Two-Fluid (COBRA-TF). COBRA-TF, designed by Pacific Northwest Laboratory, represents a two-fluid, three-field (continuous liquid, continuous vapor and entrained liquid drop) representation of two-phase flow. For heat transfer from and within the solid structures in contact with the fluid, a finite difference and semi-implicit numerical technique on an Eulerian mesh is used to solve conservation equations for each of the three fields. Even though the code is capable of predicting two-phase flow response of a system, it only predicts deterministic results without uncertainty bounds. Therefore, uncertainty equations based on Aydogan’s sampling uncertainty method are implemented into COBRA-TF to obtain uncertainty bounds of code predictions. The V&V steps of US-NRC’s Regulatory Guide 1.203 (Rg 1.203) are followed as a guideline after the code updates. Several code-to-data comparisons are done in the process of V&V: single phase pressure drop, two phase pressure drop, void distribution, critical power and dry-out location. Uncertainty bounds of code predictions are calculated and compared with the experimental uncertainty bounds. An experimental database which covers various two phase flow experiments, boundary conditions (mass flow rate, pressure and inlet enthalpies), 1/1 scale nuclear fuel bundles, axial and radial power distribution is selected for the purpose of this study. The uncertainty results of new uncertainty equations coded in COBRA-TF are satisfying.
Use of Shock Tubes for Blast Testing
Authors: Whang Chong , Chilton Warren , Chan Philemon
Published: April 2014

A computational fluid dynamics (CFD) study was carried out with data comparison to provide guidance for the control of open shock tube wave expansion to simulate field blast loadings for the conduct of biomechanical blast overpressure tests against surrogate test models. The technique involves the addition of a diffuser to the shock tube to prevent overexpansion before the shock wave impacts the test model. Mild traumatic brain injury (mTBI) has been identified as the signature injury for the conflicts in Iraq and Afghanistan, and blast overpressure from improvised explosive devices (IEDs) has been hypothesized as a significant mTBI risk factor. Research in the understanding of the mechanism of blast induced mTBI has been very active, which requires blast testing using animal and physical models. Full scale field blast testing is expensive. The use of shock tubes is clearly a viable cost effective laboratory method with many advantages. CFD simulations with data comparison show that without a diffuser, the shock wave exiting the tube tends to over expand producing an incident waveform with a short positive duration followed by a significant negative phase that is different from a Friedlander wave. However, the overexpansion effects can be mitigated by a diffuser. Shock tube tests also support the simulation results in which a diffuser improves the waveform from the shock tube. CFD simulations were validated by shock tube tests.
Controlled Efficiency During Drilling With a High Intensity Beam
Authors: Wu J. H. , Chao T. C. , Wei P. S.
Published: April 2014

Drilling with a high intensity energy beam can be incapable if the keyhole induced is collapsed. In this work, we identify the conditions for the keyhole collapse during high power density beam drilling from fundamental principles of thermal physics. The approach adapted is to probe the supersonic flow behavior of the two-phase vapor-liquid dispersion in a vertical keyhole of varying cross-section, paying particular attention to the transition between the slug and annular flows. It shows that the keyhole collapse occur from entrainment around the keyhole wall resulting in a severely deformed wavy shape of the inner liquid surface of the keyhole. This work provides a critical investigation to reveal incapability of drilling encountered in materials processing, packaging and manufacturing technologies.
Structure and Property of Sub-Zero Processed Cold Work Die Steel
Authors: Das Debdulal , Ray Kalyan K. , Dutta Apurba K.
Published: April 2014

This study examines the influence of different sub-zero processing routes on microstructure and mechanical properties of a cold work tool steel. Incorporation of controlled sub-zero processing cycle in between hardening and tempering treatment of tool steels increases the amount of ultrafine carbide particles with improved homogeneous distribution in addition to reduction in retained austenite content; these modifications are found to be enhanced with decreasing lowest temperature of the sub-zero processing cycle. It has been demonstrated that with reference to conventional heat treatment, sub-zero processing moderately improves hardness and marginally reduces fracture toughness but substantially enhances wear resistance of the selected steel; the extent of variations, in general, increase in the order of cold treatment, shallow cryogenic treatment and deep cryogenic treatment. The relationships of microstructural modifications with the variations of mechanical properties of tool steels due to different sub-zero processing have been established.
Fully Developed Heat Transfer in Mini Scale Coiled Tubing for Constant Wall Temperature
Authors: Ghobadi M. , Muzychka Y. S.
Published: April 2014

An experimental study on heat transfer enhancement in mini scale coiled tubing for isothermal conditions is conducted. Copper coils with three different radii of curvature (1 cm, 2 cm, and 4 cm), and in four lengths (1, 2, 3 and 4 coil turns) were used. The tube length is long enough to consider the flow to be hydro-dynamically fully developed. Hence, the effects of varying curvatures and lengths on heat transfer are studied. The pitch of the coil is restricted to diameter of the tube to minimize the effect of coiling. Dean number is used instead of Coiled number (modified Dean number), and hence, the results can be expanded to spiral and curved tubing. Water and two different silicone oils (0.65 cSt, 1 cSt) were used in the experiments to examine the effect of Prandtl number on coiled tubing heat transfer augmentation. Prandtl number from 5 to 15 is covered in this paper. A new correlation is proposed to calculate Nusselt number in fully developed coiled tubing based on the current results. In addition, dimensionless mean wall flux and dimensionless thermal length are also considered besides Nusselt, Reynolds, and Dean numbers.
Study on the Configuration Effect of a Vortex Finder for a Gas-Solid Cyclone Separator Using Eulerian-Eulerian Approach
Authors: Choi Moonho , Lee Sungwon , Ham Jin-Ki
Published: April 2014

Granular model, a part of Eulerian-Eulerian approach is implemented to improve a gas-solid cyclone separator’s performances which are largely determined by dimensions of a vortex finder. Design-Of-Experiments method analyzes the performances such as pressure loss, separation efficiency, and erosion rate of each variation model due to the change of design parameters of the vortex finder. Separation efficiencies due to the motion of solid particles are predicted according to the classical efficiency model by using the method of least square. The numerical results are validated by comparing with previously reported experimental data. The standard Stairmand design cyclone is improved judging from the reduced pressure loss by 43%, the reduced cut size by 63% and the reduced erosion rate by 2% by changing the position and the diameter of the vortex finder.
(A Review) Carbon Nanotubes Used for Renewable Energy Applications and Environmental Protection/Remediation
Authors: Wong Kaufui Vincent , Bachelier Benoit
Published: April 2014

Carbon nanotubes are surprisingly ubiquitous in their use for renewable energy applications as well as for environmental protection and remediation. Hence, this is the motivation for the current review, to investigate into their usefulness. The characteristic properties of these nanotubes is a result of their large surface areas, and their unique mechanical, electrical and chemical properties, and in no small part, due to its relatively easy manufacturability. Research has been done using carbon nanotubes for hydrogen storage, although it does not seem logical that carbon nanotubes would be very useful for this purpose. Carbon nanotubes used for solar collectors are used mainly for their improved thermal and electrical conductivities. Organic solar cells do not have a long life since they deteriorate in the sun. Research into long-lasting, yet inexpensive organic solar cells is an active area, and should continue to be so for some time. Carbon nanotubes are activated by certain chemicals. They may be used to react with solids, liquids and gases. Hence, they are employed for waste water treatment, liquid and gaseous cleanup. They may be used to remove metals as well as life pathogens. As the number of new pollutants and pathogens entering the environment multiply, research should continue to study the use of carbon nanotubes with regards prevention and remediation.
Vibration Control of a Translating Beam With an Active Control Strategy on the Basis of the Fuzzy Sliding Mode Control
Authors: Dai Liming , Sun Lin
Published: April 2014

An active control strategy is developed for nonlinear vibration control of an axially translating beam applied in engineering field. The control strategy is established on the basis of Fuzzy Sliding Mode Control. The nonlinear model governing the beam system is described with a six-degree nonlinear dynamic system. Corresponding to the multi-degree nonlinear system, the active control strategy is developed. The proposed control strategy is proven to be effective in controlling and stabilizing the nonlinear motions especially chaotic motion of the beam.
An Invariant Descriptor for the Conjugate Cooling of Discrete Heaters in a Duct
Authors: Loiola Bruna R. , Altemani Carlos A. C.
Published: April 2014

Forced convection cooling of electronic components mounted on circuit boards may be conveniently enhanced by conductive boards because they act as heat spreaders for the components’ cooling. This gives rise to a conjugate forced convection-conduction cooling of discrete components mounted on a board. An experimental investigation was performed to show that the temperatures of two thermal mockups mounted on the lower conductive wall of a rectangular duct cooled by forced airflow may be conveniently predicted by means of dimensionless conjugate coefficients g+ij. They are invariant with the heaters power dissipation and they may be grouped in a square matrix G+. The results were expressed as functions of the airflow Reynolds number, based on the duct hydraulic diameter, in the range from 1,600 to 6,500. The conjugate coefficients were conveniently obtained from tests with a single active heater at a time. Additional tests showed that for arbitrary power dissipation in both heaters, their temperatures were well predicted by the invariant conjugate coefficients. Numerical CFD simulations were also performed for conditions similar to those of the tests and the results were compared to those of the experiments.
Design for Reliability and Maintainability Cost Model
Authors: Ahmad Basel Alsayyed
Published: April 2014

In this paper, the author presents a cost model which simultaneously incorporates the abilities of two main designs. Namely, design for reliability (DfR) and design for maintainability (DfMn). DfR and DfMn have been of a great concern for designers. The focus has been more on the quality rather than aspects of reliability and maintainability of product development in general and product design in particular. However, as more awareness and attention is paid to the whole product lifecycle, more product lifecycle X-ability needs to be considered upfront at the design stage. To develop a new model, cost models of design for reliability as well as design for maintainability have been considered and evaluated. This new model, which tackles the two criteria simultaneously, has been developed and is a parametric model which allows for running sensitivity analysis based on the different aspects of reliability and maintainability.
Carrier Dynamics in Skutterudites
Authors: Guo Liang , Xu Xianfan
Published: April 2014

Ultrafast spectroscopy was used to measure the transient reflectance signal of skutterudites excited by femtosecond laser. By utilizing optical parametric amplifier (OPA), probe laser with various wavelengths was generated to detect the dynamics of varying electronic energy level, which provides information about the electronic band structure. The wavelength dependence of the relaxation process is discussed.
Identifying Magnitudes and Locations of Loads on Slender Beams With Welded and Bolted Joints Using a Strain Gage Based Force Transducer With Application to a Portable Army Bridge
Authors: Bednarz E. T. , Zhu W. D.
Published: April 2014

A strain gage based force transducer has been developed to identify magnitudes and locations of loads on non-continuous slender beams with welded and bolted joints. The slopes of the bending moment curves on the two sides of a load are calculated from measured strains on a beam. Four uniaxial strain gages are mounted to the bottom surface of the beam, with two strain gages on each side of the load. A calibration method developed earlier can be used to account for the discrepancies between the theoretical and actual scaling factors arising from stress concentrations and unpredictable stress patterns in the beams due to the presence of the joints. The force transducer methodology is experimentally validated on a continuously tapered aluminum beam with a series of welded joints, an aluminum beam with a constant cross section and a bolted joint, a half aluminum and half steel beam with two different cross sections and a bolted joint, and a full scale portable army bridge at the US Army Aberdeen Test Center.
Performance Characterization of a PDMS-Based Microfluidic Device for Detecting Continuous Distributed Loads
Authors: Cheng Peng , Gu Wenting , Shen Jiayue , Ghosh Arindam , Beskok Ali , Hao Zhili
Published: April 2014

In this paper, the performance of a PDMS-based microfluidic device is thoroughly characterized for detecting continuous static and dynamic loads. This device comprises of a single PDMS rectangular microstructure and a set of electrolyte-enabled distributed transducers. It is fabricated by a standard fabrication process well developed for PDMS-based microfluidic devices. One potential application of this device is to measure spatially-varying mechanical properties of heterogeneous soft materials, through quasi-static, stress relaxation and dynamic mechanical analysis (DMA) tests. Thus, the response of this device to three types of inputs: static, step and sinusoidal, is examined with a custom experimental setup. For the first time, the capability of using a polymer-based microfluidic device to detect sinusoidal inputs is reported. The characterized results demonstrate the potential of using this device to measure soft materials.
Stability Analysis for a Force Augmenting Device Considering Delays in the Human Model
Authors: Gadi Suresh K. , Garrido Ruben A. , Lozano Rogelio , Osorio Antonio
Published: April 2014

This paper presents a stability analysis of the interaction between a human and a linear moving Force Augmenting Device (FAD). The analysis employs the mathematical models of the human, the FAD and their interaction. As a depart from past works, this article presents a stability analysis considering time-delays in the human model. A key ingredient in the analysis is the use of the Rekasius substitution for replacing the time-delay terms. It is proved that the human machine interaction is stable when the human model has no delays. The analysis provides an upper bound for the time-delays preserving a stable interaction. Numerical simulations allow to assess the human-FAD interaction. An experiment is performed with a laboratory prototype, where a human operator lifts a load. It is observed that the human machine interaction is stable and the human operator is able to move the load to its desired position by experiencing very little effort.
Sound Transmission in a Lung Phantom Model
Authors: Dai Zoujun , Peng Ying , Mansy Hansen A. , Royston Thomas J.
Published: April 2014

Alterations in the structure and function of the pulmonary system that occur in disease or injury often give rise to measurable changes in lung sound production and transmission. A better understanding of sound transmission and how it is altered by injury and disease might improve interpretation of lung sound measurements, including new lung imaging modalities that are based on an array measurement of the acoustic field on the torso surface via contact sensors or are based on a 3-dimensional measurement of the acoustic field throughout the lungs and torso using magnetic resonance elastography. It is beneficial to develop a computational acoustic model that would accurately simulate generation, transmission and noninvasive measurement of sound and vibration within the pulmonary system and torso caused by both internal and external sources. In the present study, sound transmission in the airway tree and coupling to and transmission through the surrounding lung parenchymal tissue were investigated on a mechanical lung phantom with a built-in bifurcating airway tree through airway insonification. Sound transmission in the airway tree was studied by applying the Horsfield self-consistent model of asymmetric dichotomy for the bronchial tree. The acoustics of the bifurcating airway segments and lung phantom surface motion were measured by microphones and scanning laser Doppler vibrometty respectively. Finite element simulations of sound transmission in the lung phantom were performed. Good agreement was achieved between experiments and finite element simulations. This study validates the computational approach for sound transmission and provides insights for simulations on real lungs.
Comparative Evaluation of a Novel Concept Design Method
Authors: Rogers Damian , Salustri Filippo A.
Published: April 2014

Based on their previous work in creating a new method of design, termed the “Design by DNA” method, the authors are now experimentally validating the method against other, known methods. The goal of the experiment is to determine if Design by DNA promotes creative designs. Specifically, the authors are seeking to measure and compare creativity resulting from the use of Design by DNA and from other, known design methods. However, few have conducted empirical experiments in the past, and further, the literature on comparatively evaluating creativity of different design methods is relatively sparse. Therefore, the authors are developing a framework for defining and executing meaningful experiments that can accommodate various design methods, including Design by DNA, and also provide meaningful data to comparatively evaluate those methods, with the goal of determining whether Design by DNA impacts creativity in design. The experimental framework is described, and results of a pilot experiment are given. In that framework, creativity was characterized by novelty, usefulness, and cohesion. Due to small sample sizes, confidence in the results is not particularly high. Even so, some results do indicate several points of interest. An analysis of the results suggests that Design by DNA can offer advantages in engineering design, ranking higher in both the ‘usefulness’ and ‘cohesion’ categories of the creativity assessment. Hypotheses are given to explain why the experimental results show the slightly lower score in the ‘novelty’ category. Experiment participants were also evaluated on the NASA Task Loading Index (TLX) to evaluate how taxed they were using the different design methods and results are shown. Here, the Design by DNA method accrues better scores in 5 of the 6 NASA TLX categories, suggesting that it was less strenuous on the participants than the other methods. Statistical analysis of both the creativity scores and the TLX document shows confidence levels of between 65% and 96%, which is acceptable for very low populations. As this was a pilot experiment, the authors foresee future work to improve the results presented here. First, larger sample sizes are needed to improve statistical significance of our conclusions. Secondly, the authors wish to set out a series of experiments whereby each test is run by pitting one specific design method against the Design by DNA method, to better show a 1-on-1 comparison between the methods and highlight the strengths and weaknesses of each.
An Affordable Machining Laboratory Approach for Undergraduate Engineers
Authors: Chandrasekaran Vishnu Vardhan , Payton Lewis N. , Wortman Chase , Hunko Wesley
Published: April 2014

Designers in any industry need to understand the processes involved in making a part beforehand in order to communicate with technicians from trade schools and industry. Even a simple engineering drawing can often not be created due to process limitations (e.g., a perfectly drawn internal 90 degree angle in a CAD drawing does not occur in nature OR in a machine shop). This paper describes an affordable way to teach manufacturing to undergraduate engineering students and in the process provide them with hands on training in a machine shop environment. The goal here is not to create machinists, but to enable future Engineers to understand and talk with designers/machinists. The theme here is not to spend on expensive super machines but on simple machines as emphasized in the Toyota Production System. Students learn the techniques that let technicians produce perfect parts on imperfect, simple machines. The result for Auburn University has been an affordable laboratory that mutually supports undergraduate students, graduate research students, and the university as a whole.
Path Planning for Collision Avoidance Maneuver
Authors: Moshchuk Nikolai , Chen Shih-Ken , Zagorski Chad , Chatterjee Amy
Published: April 2014

This paper summarizes the development of an optimal path planning algorithm for collision avoidance maneuver. The goal of the optimal path is to minimize distance to the target vehicle ahead of the host vehicle subject to vehicle and environment constraints. Such path constrained by allowable lateral (centripetal) acceleration and lateral acceleration rate (jerk). Two algorithms with and without lateral jerk limitation, are presented.

The algorithms were implemented in Simulink and verified in CarSim. The results indicate that the lateral jerk limitation increases time-to-collision threshold and leads to a larger distance to the target required for emergency lane change. Collision avoidance path without lateral jerk limitation minimizes the distance to the target vehicle and is suitable for path tracking control in real-time application; however tracking such a path requires very aggressive control.
An Investigation on Vehicle Active Suspension and Anti-Lock Braking System Coordination Control
Authors: Liang Shi-jie , Chen Xiao-kai
Published: April 2014

This paper made an investigation on the coordinated control scheme of vehicle anti-lock braking system (ABS) and vehicle active suspension. The objective of this investigation is to obtain the maximum braking force on the road and to minimize the stopping distance and meanwhile maintain vehicle directional stability and maintain ride comfort. The controller was designed by using the fuzzy model control theory and was implemented under the Matlab/Simulink software environment. A 7-DOF-vehicle model was used to consider the influences of the non-linearity of tire and suspension. The simulation tests were carried out in various conditions. The action of the ABS combined with active suspension and the effects of applied suspension force on braking performances were examined. The simulation results show that for a particular vehicle there exists an optimal application of the suspension force. Compared with an ABS system without combing active suspension, the proposed control scheme can improve braking performance significantly.
The Active Control of Vibration and Power Flow in the Crossing-Shaped Plate Structure
Authors: Chen Zhao Bo , Li Jia Xing , Jiao Ying Hou
Published: April 2014

The power flow active control and vibration energy propagation of crossing-shaped plate with simply support boundary conditions using piezoelectric patch as actuators are studied. The combination of modal method and traveling wave method is employed to obtain the accurate analytical solution. The feedforward filtered-X least mean square (LMS) algorithm is used to obtain the optimal control moment for minimizing the power flow propagation in the plate structures. The results have shown that the vibration energy and power flow can be well controlled by the piezoelectric actuators. The different locations of piezoelectric actuators can introduce obvious fluctuation on the control results in the lower frequency range, and the fluctuation becomes more obvious in the higher frequency range.
Examining Effects of Sulfur Poisoning on Ni/YSZ Solid Oxide Fuel Cell Anodes Using Synchrotron-Based X-Ray Imaging Techniques
Authors: Harris William M. , Lombardo Jeffrey J. , Nelson George J. , Chiu Wilson K. S. , Lai Barry , Wang Steve , Vila-Comamala Joan , Liu Mingfei , Liu Meilin
Published: April 2014

Fuel flexibility is widely considered one of the most significant advantages of solid oxide fuel cells (SOFC). However, the presence of small amounts of sulfur or other impurities in the gas stream can have a serious impact on cell performance [1–10]. Under certain conditions, hydrogen sulfide (H2S), even at the ppm level, can lead to the formation of bulk nickel-sulfides within the conventional Ni–yttria-stabilized zirconia (Ni-YSZ) anode of SOFC’s [9]. Understanding the distribution of these sulfides is critical to describing their effects on the electrochemical activity of the cell.
Characterization of Real Time Producer Gas Generation From Paper Sludge Gasification
Authors: Shi Yunye , Sharma Tejasvi , Ratner Albert
Published: April 2014

Biomass Gasification is incomplete combustion of biomass resulting in production of combustible gases consisting of Carbon monoxide (CO), Hydrogen (H2) and traces of Methane (CH4), the mixture of which is called producer gas. Producer gas can be cleaned and directly used in internal combustion engines or can be converted to various attractive biofuels.

The paper sludge is a byproduct produced from recycled cardboard and into pallets. This paper is focused on gasification of paper sludge and its real-time gas evolution through this process. Variables include temperature; equivalence ratio and superficial velocity were tested and analyzed. Results demonstrate that CO2 and H2 formation is favored at higher temperature and higher oxygen concentrations. CO production is ruled by oxidation and water shift reactions but it is difficult to determine from two single variables.
Numerical Investigation to Assess an Optimal Blade Profile for the Drag Based Vertical Axis Wind Turbine
Authors: Roy Sukanta , Saha Ujjwal K.
Published: April 2014

Rapid depletion rate of fossil fuels with an increasing energy demand and their high emission are imposing the evolution activities in the arena of renewable energy. To meet the future demands of renewable energy sources, wind energy is a very promising concept. In this feature, the drag based vertical axis wind turbines (VAWTs) are suitable for small scale wind energy generation for decentralized locations. However, these turbines have low power and torque coefficients as compared to other wind turbines. Numerous blade shapes have been proposed till now to improve the performance of these turbines. In the present paper, a computational study has been performed to simulate the air-flow over different blade profiles using shear stress transport (SST) k–ω turbulence model. The results obtained are validated with the available experimental data. In the dynamic simulations, the power and torque coefficients are calculated considering the blade arc angle as the variable shape parameter. The effects of drag and lift forces on the variable blade shapes are also studied in static simulations at various angular positions. The present paper tries to demonstrate an effective computational methodology to predict the flow behavior around a drag based VAWT. Through this study, it has been found possible to select an optimal blade shape from the point of its aerodynamic performance.
Design and Manufacture of a Solar-Electric Snow Melting Device for Making Potable Water on Mt. Rainier
Authors: Hopple Whitney , Parmigiani John
Published: April 2014

Every Spring and Summer, thousands of hikers attempt to summit Mt. Rainier. Many of those hikers stop at Camp Muir, a base camp at 10,000 feet, where they can use restrooms, camp overnight, or refill water bottles before continuing their climb. Camp Muir currently uses a gas system to melt snow into potable water, requiring a tank of propane to be flown by helicopter to the camp at the beginning of each season. This system is costly and not environmentally-friendly. International Mountain Guides (IMG), one group who organizes trips in small groups, wants to replace this water production system with one that incorporates green energy. This publication examines possible designs of a new snow-melting device, describes the selected design, and outlines future testing and evaluation. Several models were considered in the design process that use readily available resources and provide constant power output. During hiking season, Camp Muir is often clear and sunny but can have high winds, meaning solar and wind energy are viable options as energy sources. However, wind speeds could be fast enough at high altitudes to damage a small device, resulting in solar energy as the selected power method. Since water production could not be limited by environmental conditions like cloudy weather, the device was designed to convert and store electrical energy. The current design of the device is portable, utilizes one solar-electric cell, and increases efficiency by recirculating melted water in addition to directly heating the snow. It requires minimal interaction and maintenance by the user. Solar-PV panels are used with rechargeable batteries to provide a constant source of power any time of day. Charged batteries are connected to the heating tank. Then, users fill the tank with snow and close the lid. The battery connects to a heating device that melts contacting snow. The melted snow is then recirculated using a pump over the top of the remaining snow. A filter with larger grating is used in the tank to filter larger debris, such as sticks and small stones, while a hand pump with a finer filter is used to both clean and extract the produced water. Early prototypes of the device are currently being constructed, tested, and evaluated. The first renditions of this design will be analyzed to ensure that they meet the desired water output using the available power input from the solar panels. The final device will be completed in September of 2013.
Finite Element Simulation of Ultrasound Propagation in Trabecular Bone
Authors: Vafaeian Behzad , Wu Yuchin , Doschak Michael R. , El-Rich Marwan , El-Bialy Tarek , Adeeb Samer
Published: April 2014

Quantitative ultrasound is used to identify healthy versus osteoporotic bone. However the physics of ultrasound propagation in trabecular media is still not sufficiently understood. This lack of understanding is reported to be an obstacle in further development of this bone assessment technique. Numerical models of wave propagation stand as a potentially successful tool to explain the various experimental observations. The main issue in the numerical modeling of wave propagation in trabecular bone is the complex geometry of the trabecular structures surrounded by a fluid (bone marrow). So far, the complex geometrical domain of trabecular structures has been approximated by finite difference grids for wave propagation analyses. In this work, numerical simulation of ultrasound propagation into trabecular bone sample is performed using the finite element method (FEM). A new procedure for numerical modeling of trabecular bone tailored for the FEM is introduced. The entire complex trabecular geometries of two cubic bone samples are reconstructed using computed microtomography data. For the first time a three dimensional finite element mesh using tetrahedral elements is generated for the two-phase medium of a trabecular bone. Separate meshes for the bony part and the filling marrow (considered as non-viscous water) are generated and acoustic-structure interaction condition is imposed on their interface. It is shown that the three-dimensional simulation using the FEM can predict ultrasound propagation phenomena observed in experiments: linear dependency of attenuation on frequency, the effect of bone volume on the attenuation and speed of sound, and the propagation of fast and slow waves. Moreover, the broadband ultrasound attenuation (BUA) for two ultrasonic signals propagating into a healthy and an osteoporotic sample are compared. A distinguishable difference in BUA between the two samples is observed expressing lower BUA for osteoporotic bone. Our developed model is the first three-dimensional finite element analysis model to compare the ultrasound propagation in healthy versus osteoporotic bone. The developed model can be further utilized as a tool to explain various experimental observations of quantitative ultrasound of bone.
Numerical Investigation of Fins Effect for Melting Process of Phase Change Materials
Authors: Varol Yasin , Okcu Mutlu
Published: April 2014

The present study numerically explores the melting process of a phase change materials in a rectangular geometry. More specifically, it investigates flow field, thermal phenomena, detailed phase and melting process by means of numerical simulation which is using as parameter; melting temperature, latent and specific heat capability, thermal conductivity and density in solid and liquid states, are based on paraffin wax. The study is performed for melting in rectangular container of without fin and 5 fins, when the wall temperature is uniform. Transient numerical simulations are performed using the ANSYS-Fluent 12.0 commercial software. The simulation results show that the transient phase change process depends on PCM properties, thermal condition and geometrical parameters of system. It includes the paraffin wax properties, thermal difference between hot and cold wall, and number of fins in the rectangular container. Results also indicate that the presence of fins embedded in the container significantly accelerates the melting process.
Fully Lagrangian Modeling of Two-Phase Impulse Microjets
Authors: Lebedeva Natalia , Osiptsov Alexander , Sazhin Sergei
Published: April 2014

A new fully Lagrangian approach to numerical simulation of 2D transient flows of viscous gas with inertial microparticles is proposed. The method is applicable to simulation of unsteady viscous flows with a dilute admixture of non-colliding particles which do not affect the carrier phase. The novel approach is based on a modification and combination of the full Lagrangian method for the dispersed phase, proposed by Osiptsov [1], and a Lagrangian mesh-free vortex-blob method for Navier-Stokes equations describing the carrier phase in the format suggested by Dynnikova [2]. In the combined numerical algorithm, both these approaches have been implemented and used at each time step. In the first stage, the vortex-blob approach is used to calculate the fields of velocity and spatial derivatives of the carrier-phase flow. In the second stage, using Osiptsov’s approach, particle velocities and number density are calculated along chosen particle trajectories. In this case, the problem of calculation of all parameters of both phases (including particle concentration) is reduced to the solution of a high-order system of ordinary differential equations, describing transient processes in both carrier and dispersed phases.

The combined method is applied to simulate the development of vortex ring-like structures in an impulse two-phase microjet. This flow involves the formation of local zones of particle accumulation, regions of multiple intersections of particle trajectories, and multi-valued particle velocity and concentration fields. The proposed mesh-free approach enables one to reproduce with controlled accuracy these flow features without excessive computational costs.
Theoretical and Experimental Analysis of Active Valve Pumping for High Flow Rate Applications
Authors: Kumar Karthik , Besharatian Ali , Bernal Luis P. , Peterson Rebecca L. , Najafi Khalil
Published: April 2014

A new valve-only micropump structure for gas applications is proposed consisting of electrostatically actuated checkerboard microvalves with dual cavities. The valve-only multistage peristaltic design minimizes complexity and footprint of the device, which allows operation at high frequency, better sealing and efficient operation. A previously developed reduced order model is used to design and analyze the performance of the system. In this paper the effect of the cavity height on the performance and stability of this system is explored. The fabricated micropump produced a flow rate of 140 μl/min at 1 kHz operation despite the cavity and membrane resonance being > 20 kHz. Four micropumps having cavity heights of 45, 60, 90 and 120 μm are explored in the modeling efforts using sinusoidal waveforms. It is found that an optimum cavity height exists which maximizes pump performance. Decreasing the cavity height below this value increases acoustic pressure damping, which in turn increases instability of the system.
Investigation of Thermal-Hydraulic Field in the Annular Channel Around the Heated Wall of the Fuel Rod
Authors: Lavicka D. , Knapp Y. , Polansky J.
Published: April 2014

Experimental measurement serves for investigation of temperature field in the annular flow channel along the heated wall of the fuel rod. Research focuses on the issue of heat transfer into the coolant at two-phase turbulent flow. Two-phase turbulent flow contains a large quantity of bubbles and, with heat transfer; it represents a very complex process. The annular flow depends on the application of spacers that affect the flow and temperature field in the flow channel at the fuel rod model. The fuel rod represents the fuel cluster in nuclear pressurized water reactor (PWR) of the VVER type.
Optimization of the Angle of Attack of Delta-Winglet Vortex Generators Over a Bank of Elliptical-Tubes Heat Exchanger
Authors: Godazandeh K. , Ansari M. H. , Godazandeh B. , Ashjaee M.
Published: April 2014

In order to reach a more efficient and compact heat exchanger, it is essential to optimize the design, having in mind the impact of different geometrical parameters. Many of the previously cited studies in the area of heat transfer enhancement using vortex generators were confined only to defined points in the possible design space. Thus, a multi-objective optimization study is particularly suitable in order to cover this space entirely. A CFD simulation along with Pareto method were used to simulate the air flow and heat transfer and optimize the design parameters. The angle of attack of a pair of delta-winglets mounted behind each tube is varied between β = −90° and β = +90°. Three elliptical tube rows with inline arrangements are investigated for Reynolds numbers from 500 to 1500 (based on the inlet properties). Use of delta-winglets as heat transfer enhancement elements increases the performance of elliptical-tubes heat exchanger. This enhancement is mainly due to the fact that delta-winglets increase the level of vorticity inside these devices and thus the mixing of the fluid is enhanced.
Modeling and Simulation Method Comparison for the Lotka-Volterra Model
Authors: Vaghei Yasaman , Sarbaz Yashar , Ghanbari Ahmad
Published: April 2014

The Lotka-Volterra or predator-prey models contain a pair of first order, non-linear, differential equations, which describe the dynamics of two species interaction in biological systems. Hence, accurate simulation strategies development for mentioned equations is crucial. In this paper, first, the presented model equations are simulated by ARX, ARMAX and BJ parametric models of the Identification Toolbox in MATLAB software. Afterwards, this simulation has been done in the Neural Network Toolbox by Feed-Forward and Elman networks with equal number of neurons, layers and same transfer functions. Finally, the results of these two simulations have been compared to introduce the best simulation methodology. It is shown that more accurate results are achieved by Elman network. In addition, the paper demonstrates that the simulation error can be decreased by simply increasing the number of these neural networks’ neurons.
Aerodynamic Focusing of Microparticles in Gas Flows With Shock Waves
Authors: Osiptsov Alexander , Golubkina Irina , Rybdylova Oyuna
Published: April 2014

The effect of aerodynamic focusing of microparticles in gas-particle flows is employed mainly for creating collimated particle beams. These beams are used in various technical applications, such as coating, “direct-write”, surface processing technologies, needle-free injections, etc. In this study, we propose and investigate two new flow schemes in which the effect of aerodynamic focusing of small low-inertia particles may be realized in high-speed gas flows with shock waves. The first one is a steady-state dusty-gas flow behind the point of interaction of two crossing shock waves. The convergence of the carrier-phase streamlines and the presence of particle inertia result in the formation of a high-concentration particle beam behind the shock interaction point. In the second flow scheme considered, the particle focusing effect is attributable to the action of the Saffman lateral force, exerting on the particles in boundary layers behind a shock wave travelling in a narrow channel with a constant cross-section. In both cases, the ranges of governing parameters are found for which the focusing is “optimal”, i.e. a very thin collimated beam of microparticles is formed.
Development of Bio-MEMS Device for Cell Cluster Patterning by Using Dielectrophoresis Method
Authors: Murakami S. , Morita Y. , Nakamachi E.
Published: April 2014

Recently, the investigation of cell-activation and tissue regeneration process has shown the great progress in the biomedical and biomechanical research fields. In this study fabricated Biomedical-Micro Electric Mechanical System (Bio-MEMS) to examine accurately the cell activation by introducing the cell patterning assignment technique, which consists of the photolithograph method to generate the MEMS device and the cell patterning technique by using the dielectrophoresis (DEP) method.

In the development of Bio-MEMS devices for cell culture and micro-bioreactor system, unresolved subjects, 1) the fundamental mechanism of cell activation, 2) the flow control of culture medium 3) the accurate cell pattern technique and 4) the implementation of positive DEP methods, are remained. In this study, we fabricate 2-D patterns of point by using the DEP method introducing the positive effects and the trap method by employing the gravity effect and the adhesion technique, to reveal the fundamental mechanism of cell activations, such as the nerve cell axon extension.

We succeed to establish the cell patterning technique by using a novel electrode design technique, such as 2-D patterns of point. The results is shown that our novel approach using comprehensive designed electrodes is superior to cell patterning. Therefore, our device able to produce neural network consists of a large number of cells.