bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Skewing of Contact Face on Performance of Wave Rotor Refrigerators and Superchargers
Authors: Dai Yuqiang , Liu Fengxia , Wu Jintao , Wei Wei , Hu Dapeng , Liu Xuewu 
Published: April 2014

As a novel generation of rotational gas wave machines, wave rotor machines such as wave rotor refrigerators (WRR) and wave rotor superchargers (WRS) are unsteady flow devices. In their passages two gas streams (with different pressure or even different phases) comes into direct contact can exchange energy due to the movement of shock waves and expansion waves. A detailed study shows that, when rotor channels open to the high pressure port gradually, the contact face in rotor channels inevitably skews, which is always accompanied with reflection of shockwaves. This causes very large energy dissipation and influences adversely on the refrigeration performance of WRR or the supercharging performance of WRS. In this work, factors such as centrifugal forces, Coriolis forces, gradual channel opening and gradual channel closing, etc, which influence the wave transportation and skewing of shock waves and contact faces are studied by means of computational fluid dynamics and experiments.
The skewing of contact faces causes uneven distribution of velocity and large local loss. With rotation Mach number smaller than 0.3, the skewing of contact face can be alleviated. To reduce the adverse influence of rotation Mach number, a smaller rotor channel width or higher rotational speed is necessary.
The rotation effect plays an important role for the skewing of gas discontinuities. Both the centrifugal and Coriolis forces of wave rotor cannot be ignored with the Rossby number of 1.3∼3.5. To reduce the skewing loss of contact face, a lower rotational speed seems necessary. The rotation speed of wave rotors has dialectical influences on the skewing of shock waves and contact faces.
The jetting width of high pressure port is the key factor of the gradual opening of rotor channels. A feasible way to reduce skewing losses of gas waves is to optimize the ratio between high pressure port width and channel width. The validation experiments have got at least 3∼5% rise of isentropic efficiency for WRRs.
Constructal Design for Efficiency: The Case of an Entropic Wall With Circulating Water
Authors: Dumas Antonio , Trancossi Michele , Madonia Mauro 
Published: April 2014

This paper presents an effective analysis on the relation between the changing architecture of a flow system and the maximization of global performance under constraints. An entropic wall with circulating water based on LESP concept has been analyzed. It is a wall with good acclimatizing properties generated by circulating water, which is thermally stabilized by exchanges in the ground. The system has been considered by different levels of complexity. The thermal structure is optimized by considering the system as a sequence of building blocks with assemblies of stepwise larger sizes: an entire wall and the entire building.
The optimal flow network is tree shaped. Different levels of optimization have been performed according to the different scale levels. On an elemental scale is has been optimized the properties of the single elemental block constitutive of the considered wall. On a single wall level, the system has been optimized to optimize internal fluid distribution system, maximizing the thermal uniformity and minimizing the weight of the wall.
The calculation process have been improved enriching the Constructal approach by a novel calculation method which has been defined for introducing more systemic algorithmic calculations at engineering level. This method has been defined as Constructal Design for Efficiency.
Effect of Extrusion Parameters on Mechanical Properties of Al6061-Ni-P Coated SiC Composites
Authors: Suryanarayana Ramesh Chinnakurli , Ramakrishna Sikhakolli , Attaullah Ummar Khan , Badnur Smitha Hanumantha , Saheb Kumar 
Published: April 2014

Extrusion of metal matrix composites (MMCs) is a very challenging one where in the bond between the reinforcement and the matrix alloy is crucial in getting high quality extrusions for industrial applications. In recent years researchers are focusing on developing aluminium based composites with metallic coated reinforcement to achieve good interfacial bonds to ensure smooth load transfer from the matrix on to reinforcement. However no information is available as regards hot extrusion of metallic coated reinforced MMCs. In the light of the above, the present work focuses on a systematic investigation on effect of extrusion process parameters on mechanical properties of Al6061-Ni-P coated SiC composites.
From the investigation, it is observed that hardness, yield and ultimate strength of Al2014-SiC (Both uncoated and Ni-P coated) composites are higher when compared with the matrix alloy for all the extrusion ratios studied (4:1,5:1,10:1,15.5:1) at a given extrusion temperature. However, the ductility of composites decreases with increase in extrusion ratios. Further, heat treatment has a significant effect on the studied mechanical properties. Increase in extrusion temperatures at a given extrusion ratio has resulted in decrease in hardness and strength properties of both matrix alloy and developed composites.
Numerical Modelling and Experimental Validation of Intervertebral Discs
Authors: Azarnoosh Marzieh , Stoffel Marcus , Weichert Dieter 
Published: April 2014

Over the last several decades investigations of replacement material for intervertebral disc (IVD) have been an important topic in medical research. The challenge is to create materials whose mechanical behavior ideally matches that of the articular cartilage comprising the native discs. Thus, the study of articular cartilages underlying mechanical characteristics is a key issue for the successful development and refinement of replacement materials.
Using both experimental and cartilage histostructural data, including fiber orientation, a visco-hyperelastic-diffusion (VHD) material model is developed and implemented. This allows us to numerically study the mechanical behavior of an IVD consisting of a cartilaginous ring surrounding a fluid core.
In this work, a three dimensional finite element (FE) model is developed to simulate the behavior of an IVD under various loading conditions. Finally, model parameters are iteratively determined by comparing the simulation results to compression tests on corresponding discs performed in a MTS machine with a tempered nutrient solution.
Set-Based Concurrent Engineering for Preserving Design Bandwidth in Product and Manufacturing System Platforms
Authors: Michaelis Marcel T. , Levandowski Christoffer , Johannesson Hans 
Published: April 2014

Assembling products to order or applying straightforward configuration, such as scaling, allow the reuse of ready-designed physical components in high volumes. However, not all companies can exploit economies of scale in this way. They are burdened with additional design work, as requirements on functionality and performance differ among product variants or change over time. Such companies need artifact models and engineering processes that help them manage and develop for variety.
Set-based concurrent engineering has been proposed for dealing with a variety of concepts during development that lead to a single product while storing knowledge gained. This paper adapts this thinking to the preparation and use of product and manufacturing system platforms. Here, the output is not a single product. Rather, a set of design solutions for products and manufacturing systems is designed that delivers flexibility in functionality and performance. In this paper, we call this built-in flexibility design bandwidth.
The paper builds on an integrated artifact model for products and manufacturing systems. The model captures the rationale behind existing designs with their functionality. Here it is combined with principles of set-based concurrent engineering to outline a process for its preparation and use in cases of insufficient bandwidth that require additional designing. The preparation and use are illustrated by applying the model to an example where bandwidth is expanded and preserved.
Design for Multiple Industries: A PDP (Parallel Distributed Processing) Approach
Authors: Fukuda Shuichi 
Published: April 2014

A Parallel Distributed Processing (PDP) or Neural Network model is proposed. It restructures our knowledge and experience in product development in the form to achieve widest applicability.
Up to now, product developments have been discussed within one company or one industry at the widest. But in order to increase productivity and to reduce time, cost and energy consumption by a large margin, a great change in our way of thinking is called for. We need to go beyond one company or one industry and team up with other industries.
Just as Concurrent Engineering succeeded in one company or in one industry by bringing downstream information upstream and by processing them concurrently, this goal can be realized if we introduce Parallel Distributed Processing (PDP) model. PDP is more popularly known as Neural Network.
As the relationship between raw materials, intermediate products and final products can be described as a neural network, this goal can be achieved if knowledge and experience are shared across different industries and re-assembled at the intermediate components layer. Then, final products can be developed as the combination of these intermediate components just like Lego.
This not only eliminates overlaps between industries, but this-organizes our knowledge and experience into the form applicable to wider applications and wider areas so that it brings forth greater flexibility in product development.
In short, a PDP or Neural Network model proposed here is the restructuring of our knowledge and experience in order to expand their applications to the widest.
Such restructuring not only achieves widest applicability, but it also helps introduce autonomous distributed economy. Our economy has been too much centralized. If we change our economy system to autonomous distributed system, countries can team up more effectively and develop Win-Win relations, which is most important in this age of globalization.
A Simplified Model for the Flow Inside Cascade Impactor
Authors: Nemati Mehr Seyyed Mahdi , Sohrabi Salman , Falsafi Pedram , Gorji Paniz 
Published: April 2014

In this paper we developed a new mathematical model for the flow inside cascade impactors and via this simplified model, we determined the particle size distribution by a fast and low cost computational method. Using cascade impactors for determining the particle size distribution, one can use comprehensive CFD methods to fully simulate the particle traces. Although the results from those CFD analyses can be very accurate, usually that is not a time and cost efficient routine. In contrast, we showed that by using our proposed calculation we can estimate the particle size distribution very fast and yet with the slight error — comparing to the results from CFD method.
Cascade impactors are being used to measure the range of substances moving through an opening and determine the particle size of distributed substances. Air flow containing aerosol entering in each stage, after colliding vertically with a plate will deviate 90 degrees from its original direction. Larger (massive) particles cannot follow the flow because of their larger linear momentum. Hence, they will deviate from the flow and deposit on the plate instead. The mass difference before and after the experiment represents the deposited mass in each stage. By integrating multiple uniquely designed stages into one impactor, we can determine size of particles in the flow. Typical cascade impactors consist of up to ten stages in which different size of aerosols are being separated.
This paper presents a simple model for the flow in one single stage of a cascade impactor. Flow inside cascade impactor is approximated by stagnation point potential flow with the stream function of Psi = Axy, and particles are tracked by velocity verlet algorithm. Absorbed particles are associated with unit value; otherwise they are associated with zero. It is assumed that particles in entrance have random size distribution and location. Drag, Saffman and Brownian forces are taken into account in this model for different particle sizes. The results are discussed in detail and compared with data driven from different approaches in the literature.
Nucleate Pool Boiling Enhancement Experiments for Heat Transfer Laboratory
Authors: Dikici Birce , Eno Edidiong , Compere Marc 
Published: April 2014

Boiling heat transfer is used in variety of industrial processes and applications, such as refrigeration, vapor cycle power generation, heat exchangers, petroleum refining, and chemical manufacturing. It is also used in cooling of high power electronic components, nuclear reactor cooling and seawater desalination. Enhancements in boiling heat transfer processes are critical for making these applications more energy efficient.
The aim of this paper is to demonstrate the water pool boiling phenomena under the influence of surfactant additives. The test setup has multiple benefits. First, the test setup enhances teaching in Heat Transfer, Transport Phenomena, Fluid Mechanics, and Renewable Energy through in class demonstrations and student experiments. Second, the test setup provides a platform for research in boiling enhancement. This apparatus will be used in the classroom for hands-on experiments and also as a diagnostic tool for boiling performance improvement methods like surfactant effects. For determining surfactant effects, different concentrations of sodium lauryl sulfate (SLS) added to pure water were tested and enhancement through surfactant is quantified.
With the integration of boiling experiments into coursework, mechanical engineering students will develop laboratory experiences to enhance the learning of basic boiling concepts. Three pool boiling projects that can be integrated into heat transfer laboratory are explained. The suggested test setup is a valuable tool for improving teaching effectiveness in both classroom and laboratory of heat transfer related classes.
Response of Post-Mortem Human Head Under Primary Blast Loading Conditions: Effect of Blast Overpressures
Authors: Ganpule Shailesh , Salzar Robert , Chandra Namas 
Published: April 2014

Blast induced neurotrauma (BINT), and posttraumatic stress disorder (PTSD) are identified as the “signature injuries” of recent conflicts in Iraq and Afghanistan. The occurrence of mild to moderate traumatic brain injury (TBI) in blasts is controversial in the medical and scientific communities because the manifesting symptoms occur without visible injuries. Whether the primary blast waves alone can cause TBI is still an open question, and this work is aimed to address this issue. We hypothesize that if a significant level of intracranial pressure (ICP) pulse occurs within the brain parenchyma when the head is subjected to pure primary blast, then blast induced TBI is likely to occur.
In order to test this hypothesis, three post mortem human heads are subjected to simulated primary blast loading conditions of varying intensities (70 kPa, 140 kPa and 200 kPa) at the Trauma Mechanics Research Facility (TMRF), University of Nebraska-Lincoln. The specimens are placed inside the 711 mm × 711 mm square shock tube at a section where known profiles of incident primary blast (Friedlander waveform in this case) are obtained. These profiles correspond to specific field conditions (explosive strength and stand-off distance). The specimen is filled with a brain simulant prior to experiments. ICPs, surface pressures, and surface strains are measured at 11 different locations on each post mortem human head. A total of 27 experiments are included in the analysis.
Experimental results show that significant levels of ICP occur throughout the brain simulant. The maximum peak ICP is measured at the coup site (nearest to the blast) and gradually decreases towards the countercoup site. When the incident blast intensity is increased, there is a statistically significant increase in the peak ICP and total impulse (p<0.05). Even after five decades of research, the brain injury threshold values for blunt impact cases are based on limited experiments and extensive numerical simulations; these are still evolving for sports-related concussion injuries. Ward in 1980 suggested that no brain injury will occur when the ICP<173 kPa, moderate to severe injury will occur when 173 kPa<ICP<235 kPa and severe injury will occur when ICP>235 kPa for blunt impacts. Based on these criteria, no injury will occur at incident blast overpressure level of 70 kPa, moderate to severe injuries will occur at 140 kPa and severe head injury will occur at the incident blast overpressure intensity of 200 kPa. However, more work is needed to confirm this finding since peak ICP alone may not be sufficient to predict the injury outcome.
Influence of Engine Harmonics on Synchroniser Mechanism Dynamics
Authors: Walker Paul D. , Zhang Nong 
Published: April 2014

Synchronizer mechanisms play an important role in the selection and engagement of gears in manual, automated manual and dual clutch transmissions (DCT). These mechanisms rely heavily on the balancing of torque loads in cone clutches, dog gears and from losses in the gearbox to ensure repeatable and reliable actuation, with excessive wear on friction and contact surfaces leading to degradation of actuation and potential mechanism failure. Dual clutch transmissions, in particular, provide a unique operating environment for synchronizers, most notably is its actuation with the engine still driving the wheels during normal driving conditions. Thus, the consideration of increased transmitted vibrations through the powertrain must be evaluated to study the impact of these vibrations on the synchronizer.
To conduct this investigation this paper develops a detailed multi-body dynamic model of a typical automotive powertrain equipped with a dual clutch transmission. This includes engine models with torque harmonics that capture the instantaneous torque variations from piston firing in the engine. As the main consideration of this paper is the influence of engine harmonics, the semi-definite powertrain model is simplified to a fixed-free system and the response of the synchronizer mechanism to harmonic torque inputs is analyzed.
Parametric analysis of the system is conducted to analyze the influence of variables — including gear ratio, torsional damper, system damping, and engine configuration — on the dynamic response of the mechanism. Results demonstrate the influence of each of these variables on synchronizer dynamics in the steady state, with stiffness of torsional damper having the strongest influence on forced vibration. Additionally, results vary significantly between single and dual lay-shaft transmissions.
Classification of Blood Flow in Cerebral Aneurysm Considering the Parent Artery Curves
Authors: Nakayama Toshio , Sugiyama Shin-ichiro , Ohta Makoto 
Published: April 2014

Background and purpose: Recently, the number of endovascular treatments has increased worldwide because of advances in minimally invasive surgery. We considered the effect of reduced flow due to stent implantation and proposed the design of stent strut pattern from the viewpoint of fluid dynamics. We developed an optimized stent strut pattern using a computational fluid dynamics (CFD) system. A classification of cerebral aneurysms was proposed using the aspect ratio (AR) and the stent strut pattern was optimized. The results of optimal stent strut pattern for reduced blood flow speed and wall shear stress were different, and the influence of the AR values was small because there was no dependence on relationship between blood flow and the AR values due to the use of a straight pipe in the parent artery. The classification of blood flow pattern in a cerebral aneurysm must consider the parent artery curves. In this study, we investigated the relationship between the blood flow pattern in cerebral aneurysms and parent artery curves using CFD.
Methods: To investigate the influence of blood flow based on the parent artery curve, the parent artery shape was constructed as follows. Patient-specific parent artery shape with a cerebral aneurysm was reconstructed using OsiriX. Center line was extracted using a vascular modeling tool kit. The parent artery shape was reconstructed based on this center line using CAD. The diameter of the parent artery was 4 mm. The cerebral aneurysm shape was a combination of a straight pipe and a half sphere, and the AR value was fixed at 1.0. The cerebral aneurysm position varied from the original position to a 180° rotated position.
Tetrahedral numerical mesh was generated with a commercial mesh generator (ICEM CFD 14.0; Ansys Inc.) for the CFD analysis. The numerical blood flow simulation was performed on a supercomputer using the commercial ANSYS FLUENT 6.3 software package and the finite volume method, and a steady flow simulation was performed. Boundary conditions were set for velocity at the inlet, pressure at the outlet, no-slip parent artery, and stent surface. Reynolds numbers at the inlet determined from the mean blood flow speed were 240 and 600.
Results and discussion: In this study, we revealed the blood flow pattern in some cerebral aneurysms using CFD. The pattern in a cerebral aneurysm was influenced by the aneurysm direction and parent artery curves. The blood flow pattern in a neck cerebral aneurysm was classified into two types.
Evaporative Particle Deposition on Superhydrophobic Surfaces
Authors: Dicuangco Mercy , Dash Susmita , Weibel Justin A. , Garimella Suresh V. 
Published: April 2014

The ability to control the size, shape, and location of particulate deposits is important in patterning, nanowire growth, sorting biological samples, and many other industrial and scientific applications. It is therefore of interest to understand the fundamentals of particle deposition via droplet evaporation. In the present study, we experimentally probe the assembly of particles on superhydrophobic surfaces by the evaporation of sessile water droplets containing suspended latex particles.
Superhydrophobic surfaces are known to result in a significant decrease in the solid-liquid contact area of a droplet placed on such a substrate, thereby increasing the droplet contact angle and reducing the contact angle hysteresis. We conduct experiments on superhydrophobic surfaces of different geometric parameters that are maintained at different surface temperatures. The transient droplet shape and wetting behavior during evaporation are analyzed as a function of substrate temperature as well as surface morphology. During the evaporation process, the droplet exhibits a constant contact radius mode, a constant contact angle mode, or a mixed mode in which the contact angle and contact radius change simultaneously. The evaporation time of a droplet can be significantly reduced with substrate heating as compared to room-temperature evaporation.
To describe the spatial distribution of the particle residues left on the surfaces, qualitative and quantitative evaluations of the deposits are presented. The results show that droplet evaporation on superhydrophobic surfaces, driven by mass diffusion under isothermal conditions or by substrate heating, suppresses particle deposition at the contact line. This preempts the so-called coffee-ring and allows active control of the location of particle deposition.