bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Modern Passenger Side Door Types and Integration With Car Design for Heavy Rail and Light Rail Applications in North America
Authors: Donohue Brian P.
Published: November 2010

In 2007–08, a study of passenger side entrance door types and integration with overall car design was conducted by Parsons Brinckerhoff (PB) for a client in the State of California. As found on many other intercity and commuter operations in North America, the client had for years endured a variety of technical challenges with the side entrance doors that had compromised passenger service and safety. Recent advances in side entrance door designs and the subsequent changes to new car specifications have opened the door to solutions to many of these challenges; solutions include hardware changes to the door panels and assemblies, and intelligent systems included in software and sensors of the door control for monitoring and diagnosing door settings, operations and faults in real time. Through field inspections and equipment evaluations, this study determined that the majority of the faults were caused by contamination. A principle solution to eliminating this contamination was determined to be in the door seals and subsequent door panel type. Among the recommendations made to the client were to change from a bi-parting pocket sliding door system to a bi-parting sliding plug door system. This paper presents two portions of the PB study: 1) an overview of the technical challenges of operating intercity and commuter rail passenger service in California, and 2) an industry study that identifies the latest in appropriate technologies for service in California. Modern rail passenger cars with similar service and bi-parting pocket sliding doors are evaluated. This paper also discusses how the findings in California can be applied to other commuter, heavy and light rail transit operations in North America.
Slab Track for Shared Freight and High Speed Passenger Service
Authors: Li Dingqing , Bilow David , Sussmann Ted
Published: November 2010

This paper presents design and construction details of two types of slab track installed at the Facility for Accelerated Service Testing (FAST), near Pueblo, Colorado. Direct fixation slab track (DFST) and independent dual block track (IDBT) were installed on a 5-degree curve with 4-inch superelevation. The slab track test section was 500 feet long, consisting of 250 feet of DFST and 250 feet of IDBT. The slab track test section was designed to support 39-ton axle load train operations, while maintaining track geometry for high-speed track standards.
Maglev High Speed Rail Along the Northeast Corridor
Authors: Kinstlinger Jack
Published: November 2010

This paper summarizes parts of a feasibility study prepared by the Maryland Transit Administration for the Federal Railroad Administration on a proposed magnetically levitated train project.1 Initially the project would connect Camden Yards in downtown Baltimore with Union Station in Washington DC with a stop at BWI Thurgood Marshall Airport. Ultimately, it is proposed to extend the Project along the U.S. eastern seaboard north through Philadelphia and New York to Boston and south through Richmond, Raleigh and Charlotte in North Carolina. The paper contains an evaluation of potential air travel reduction along the east coast if maglev service were available and a comparison of energy consumption between maglev and conventional modes of travel. Finally, the paper contains estimates of reductions in carbon dioxide greenhouse gas emissions resulting from diversions of travel from autos and aircraft to the proposed maglev service along the eastern seaboard.
Local Stress Analysis and Model Test of Arch Foot for a Steel Box Arch Bridge on High-Speed Railway
Authors: He X. H. , Zhao A. H. , Scanlon A. , Peng L. P.
Published: November 2010

A large span X-style steel box arch bridge is under construction for a high speed railway line between Nanning and Guangzhou. A 1:8 scale model test of the arch foot for the bridge is described. Based on the two-step finite element (FE) analysis method using commercial software, a global FE model of the bridge and local FE model of arch foot are developed. Local stress distributions of the arch foot are obtained. Typical experimental stresses measured in the scale model are presented and compared against those obtained from FE analyses of different models. The results are used to provide recommendations for design of the bridge and other similar bridges.
Microstructural Analysis of Thermite Welds
Authors: Redkin Konstantin V. , Garcia C. Isaac , DeArdo Anthony J. , Gutscher Daniel , Kalay Semih
Published: November 2010

Thermite welding is a simple and cost-effective process widely used in the field for rail repair and joining. Despite the well-accepted use of this technology, there is a major concern regarding the soundness of the weldments which are often found to be very sensitive to wear and cracking. In order to gain a better understanding of the structural factors that contribute to the performance behavior of thermite welds, systematic microstructural analyses of a series of welds was conducted. Of particular interest in this study was to carefully examine and compare the microstructure of the weld metal, heat affected zone (HAZ) and base metal of a series of thermite welded samples with different carbon content. The results of this work revealed the presence of proeutectoid cementite along the prior austenite grain boundaries at the three locations examined. In addition, microhardness evaluation of the welds revealed that substantial softening takes place in the HAZ, independent of the chemical composition of the rails or weld processing conditions. The presence of proeutectoid cementite along the prior austenite grain boundaries and the softening that takes place in the HAZ are two of the structural factors most likely responsible for the lower than expected wear behavior observed in welded or repaired rail steels. This paper will present and discuss the microstructural and processing factors associated with the formation of proeutectoid cementite and the causes leading to the observed softening.
Determination of Longitudinal and Transverse Railway Track Resistance
Authors: Kerokoski Olli
Published: November 2010

Several national guidelines set the non-linear horizontal spring values between the railway track and a railway bridge. In Finland that is not the case. Consequently, one of the objectives of the research funded by the Finnish Rail Administration was to determine the spring values both during the elastic phase in the beginning of displacement and during the plastic phase. These values are needed, for example, to calculate the behaviour of an integral bridge-track structure. In autumn 2007 researchers from the Department of Civil Engineering at Tampere University of Technology performed field tests to measure the track resistance at a railway yard in Mellila¨, Finland. The main objectives of the experimental study were 1) to determine the longitudinal track resistance and the load-displacement relation, 2) to compare the measured values to those reported by the International Union of Railways (UIC), and 3) to determine the transverse track resistance and the load-displacement relation. The railway yard had three track test locations, two for longitudinal loading and one for transverse loading. At each location the rails were cut to a length of six to seven metres. During the longitudinal loading the track was loaded with two adjacent hydraulic jacks. Altogether eight longitudinal tests were conducted, three without a vertical load and five with a vertical load. The vertically unloaded track reached the plastic phase due to the axial load. The vertically loaded rails moved axially in their fasteners while the sleepers moved only a little in relation to them. Consequently, the track did not reach the plastic phase. The results of the longitudinal tests were reported as horizontal and vertical displacements and axial rail stresses along the rail at different phases of the axial loading. The results were presented also in tables where initial stage stiffness was presented as an elastic value [kN/m/m] and plastic track resistance in kN/m. The maximum forces per metre affecting the track without a vertical load were 13 to 15 kN/m. The maximum forces per metre affecting the track with a vertical load were 26, 15 and 31 kN/m. During transverse loading the track was loaded horizontally with an excavator bucket. Altogether five loadings with three different arrangements were performed. The loadings clearly caused curvature of the track. The results of the transverse tests were reported as displacements at different locations during different phases of loading.
Dynamic Analysis of Unstable Vibration of KTX
Authors: Kang Bu-Byoung
Published: November 2010

The acceptance test of Korean TGV imported from France has been performed in Korea. During the test, it was found that lateral vibration of car body was over the acceptable value at the tail of the train at low winter temperature. Many researches have been performed to find the cause of the vibration and its counter-measure. One of the differences between Korean TGV and French TGV is the train set formation. French TGV is operated with 10 car train set formation or two 10 car train set linked by a automatic coupler, whereas Korean TGV has 20 car formation, which are linked by articulate bogies. The purpose of this study is to verify the effects of long train set formation on vehicle dynamics as well as the train stability using vehicle model with 16 cars and 20 cars. Firstly, the reliable vehicle model which shows well the tendencies appeared in the tests with a 16 car train set on the high speed test line is required to find the cause of lateral vibration and its countermeasure. The vehicle model was made for the analysis using multibody dynamic software, VAMPIRE. The analysis results show that the secondary air spring lateral stiffness is the most influential factor to car body lateral vibration. The mode analysis results show that the least damped mode shape is similar to the vibration pattern shown in the tests that the amplitude of the motion increases along the train set and decreases in the tail part. Nonlinear transient analysis shows the similar vibration pattern along the train. The lateral vibration appeared at the speed range between 100km/h and 200km/h and disappeared at low and high speed. The mode analysis result showed that when wheel conicity increased, unstable vibration mode disappeared. And it was verified through a test that when XP55 wheels with higher conicity than GV40 that had been applied to TGV were applied to articulated bogies, lateral vibration of the last trailer car showed stable within the recommended value of acceleration regardless of outside temperature.
Taiwan High Speed Rail Viaducts: A Seismic-Safety and Passenger-Comfort Design Approach
Authors: Cheng S. H. , Yen Tony , Huang S. C.
Published: November 2010

The Taiwan High Speed Rail (HSR) line, running north ∼ south, is located at the western corridor of the island with a total length of 345 km., out of which 252 km. are continuous viaducts or bridges. This type of structure was chosen to eliminate on grade crossing for trains travelling at speed of 300 km/hr., this will also allow better land usage on either side of the line. Taiwan is a major earthquake zone, the imperative challenge for the planning and design of this world’s longest HSR viaducts is to provide controlled dynamic responses to the structure for operational safety and passenger comfort. To achieve this goal, dynamic interactions between the running high speed trains and the viaducts need to be studied comprehensively and in details. The result is a specification very different from traditional railway viaduct. SINOTECH Engineering Consultant, Ltd. was involved with this HSR project in various stages including planning for part of the alignment during project development by government agencies, and also basic and detail design of viaducts for the BOT concessionaire THSRC. In this paper an introduction is given on how the major contents of viaduct specific design specification of UIC, Eurocode, Japanese code and Taiwan local code have been combined. How Sinotech approached this challenge, the design method chosen, and a summary of bridge design related to seismic safety and passenger comfort are also described herewith. Finally, the experience gained from Taiwan HSR and suggestions for future HSR design and construction are summarized for the reference of similar projects in the future.
Key Issues on Train Line Planning for Beijing-Shanghai High Speed Railway
Authors: Nie L. , Fei D. B. , Zhou S. D. , Fu H. L. , Tong L.
Published: November 2010

The Beijing-Shanghai High speed railway line (Hereinafter referred to as “Jing-Hu HSL”) is one of the most important railway lines in the Chinese rapid passenger transportation network and will be put into operation at the end of 2011. Train line planning directly reflects the quality and competition ability of train services. The characteristics of operational conditions and passenger flow of this corridor HSL bring about a few new issues on train line planning like night train operation, train OD sets, cyclic operation, and train stop schedule. For the first issue, a large amount of long distance travel demand put forward the demand for night services, which causes great conflict with the time-window for maintenance work. The confliction can be solved by harmoniously utilizing the parallel lines. For the second one, in view of the differences of technical and economic factors between HSL and conventional railways, high frequency and medium-long distance train will dominate HSL’s train service plan rather than low frequency and long distance trains on conventional railways. Thus, part of long-distance passenger flow has to transfer at some stations. Considering the whole possible ODs over Jing-Hu HSL and the transfer condition of related stations, the optimal OD sets and corresponding transfer plan is suggested. High frequency makes HSL possible to operate trains cyclically to improve service quality. However, with too many train ODs and some special trains, e.g. night train, an incomplete cyclic train operation mode is more practical. The ODs which can provide cyclic service for Jing-Hu HSL need to be identified. For the last issue, although non-stop long-distance train is a very popular kind of service in China, it should be reconsidered for Jing-Hu HSL line because of massive intercity travel demand and regular stops required. Each of the above issues is very complex. What is more, they have close relationship between each other. Due to limited space, the methods used to solve these issues are given in conceptual way rather than detailed description of mathematical model. The research paves the way for future integration study to design an efficient, economic, convenient, and regular train service plan for Jing-Hu HSL.
Dynamic Scheduling Model and Algorithm for Dispatching Trains in High-Speed Railway Passenger Station
Authors: Yue Yixiang , Zhou Leishan
Published: November 2010

Regarding the railway station tracks and train running routes as machines, all trains in this railway station as jobs, dispatching trains in high-speed railway passenger stations can be considered as a special type of Job-Shop Problem (JSP). In this paper, we proposed a multi-machines, multi-jobs JSP model with special constraints for Operation Plan Scheduling Problem (OPSP) in high-speed railway passenger stations, and presented a fast heuristic algorithm based on greedy heuristic. This algorithm first divided all operations into several layers according to the yards attributes and the operation’s urgency level. Then every operation was allotted a feasible time window, each operation was assigned to a specified “machine” sequenced or backward sequenced within the time slot, layer by layer according to its priority. As we recorded and modified the time slots dynamically, the searching space was decreased dramatically. And we take the South Beijing High-speed Railway Station as example and give extensive numerical experiment. Computational results based on real-life instance show that the algorithm has significant merits for large scale problems; can both reduce tardiness and shorten cycle times. The empirical evidence also proved that this algorithm is industrial practicable.
The Vulnerability Assessment Method of Railway Network
Authors: Wang Wei , Liu Jun , Haiying Li , Jiang Xi
Published: November 2010

Vulnerability in the Railway system is, studied not only from the perspective of network topology characteristic but also as the problem of the level of service relative to structure, nature damage and traffic attribute. Also, emphasis is put on the function of the system rather than the physical network itself, although some of non-serviceability in the railway network is indeed caused by physical failures. The Vulnerability of railway network is thus a decisive factor not only in terms of connectivity, and serviceability, but also in terms of the transport system performance under dynamic process-traffic which should be acknowledged as an integral element within vulnerability assessment. The paper aims at investigating the most typical factors that affect the vulnerability. The vulnerability analysis must consider each factor separately, and, at the same time, as a whole. A method to measure the vulnerability is proposed. Furthermore, this assessment method is used to analyze the Chinese Railway Network (CRN).
Design Method for High Speed Wheel Profiles by Considering Rolling Radii Difference Function
Authors: Shen Gang , Zhong Xiaobo
Published: November 2010

A target-oriented method for the design of railway wheel profiles is presented. The target chosen is the rolling radii difference function which plays an important role in the dynamics of railway vehicles especially for high speed performances. A computer program based on this method has also been developed and is validated by way of examples in which wheel profiles LMA, S1002G and XP55 are investigated.
Using Public Private Partnerships to Deliver Successful Rail Projects
Authors: Higton Nick , Clark Steven L.
Published: November 2010

This paper explores the effectiveness of using Public Private Partnership (P3) deals to improve or create railway assets. The opportunities and issues involved are applicable to other asset-intensive and safety-critical utilities with a high level of human interaction and large investment needs. The authors draw upon personal experience of projects involving P3’s from the UK, Europe, North America and South America, and also privatizations and restructurings with similar characteristics. From this experience, a number of lessons are drawn of interest to suppliers, clients, promoters, and financiers of such projects. The authors conclude that P3’s are a valuable delivery mechanism for large infrastructure projects, including railways, in circumstances where there is social and economic need for the asset, but where the client’s access to capital funding is limited. There are some disadvantages for certain types of clients, which will be exacerbated when the project specification and controls are weak. Accordingly, close collaboration between the client and their professional advisors, together with a willingness to accept the strictures of a P3, are essential factors for success.
Rail-CR: Cognitive Radio for Enhanced Railway Communication
Authors: Amanna Ashwin , Gadhiok Manik , Price Matthew J. , Reed Jeffrey H. , Siriwongpairat W. Pam , Himsoon T. Kee
Published: November 2010

Robust, reliable, and interoperable wireless communications play a vital role in the success of railroad operations. This paper describes an effort towards developing a railroad-specific “cognitive radio” (Rail-CR) that can meet the needs of future wireless communication systems for railways by making positive train control (PTC) communication more interoperable, robust, reliable, and spectrally efficient, and less costly to deploy and maintain. Cognitive radios are a cutting edge research area that combines artificial intelligence (AI) with Software Defined Radios (SDRs) with the goal of improving upon existing radio performance. SDRs are radios in which capabilities are flexible due to realizing some functionality in software as opposed to a purely hardware platform. By utilizing situational awareness from the radio in the form of observable parameters, often known as ‘meters’, a cognitive engine (CE) utilizes software-based decision-making algorithms to determine if a change in the radio parameters, commonly referred to as ‘knobs’, is required based on sets of predefined goals. Additionally, learning algorithms dovetail with the decision making to enable the system to track and utilize past decisions and observations.
The Canadian Pacific DGRMS: The First Use of Deployable GRMS in a Production Mode
Authors: Bloom Jeffrey A. , Gagne Ron
Published: November 2010

The Deployable GRMS (DGRMS), which is capable of testing gage restraint at 50 mph, was originally developed for the FRA in 2004. Gage Restraint Measurement systems use a hydraulically loaded split axle to laterally push outward on each rail to expose gage restraint weaknesses. The DGRMS is the first system to utilize a deployable fifth axle instead of a running axle for this purpose. The FRA prototype system has been used in FRA research projects but not in a year-round daily production mode. Canadian Pacific Railway (CPR) procured the first production system that was installed on a box car and placed the system into service in February 2009. The first six months of service was used for equipment shakedown which resulted in a robust daily production system. The resultant system is being used year-round by CP, even on snow-covered rails. This paper describes the CP experience, the results of the test program, and new improvements in the technology.
Design and Construction Technologies
Authors: Wu Cailan , Cui Weixiao , Zhang Chengzhi , Li Huaijian , Yan Hongliang
Published: November 2010

Combining with the actual situation of China’s railway construction, this paper introduces the key technologies of design and construction of high-speed railway, such as the scheme optimization of subgrade, bridge and tunnel, technical standard, deformation control, advance geology forecast and settlement observation, etc. It also discusses the design and construction problems on the slab layout and interface of CRTS II slab track on bridge section, switch area, subgrade area and the transition with different track structures.
Examining the Role of the Hiawatha Service in the Milwaukee-Chicago Corridor
Authors: Sperry Ben , Johnson Ethan
Published: November 2010

In recent years, the policy and regulatory environment for intercity passenger rail in the United States has shifted dramatically. To support the resulting increase in intercity passenger rail planning activities, there is a need to understand the roles for passenger rail service in an intercity corridor, including who is using the service and how it is being used. Using on-board passenger survey data, this paper examines the role of the Hiawatha Service in the modal mix of the dense Milwaukee-Chicago intercity corridor. Primary trip purposes among Hiawatha Service travelers include personal trips, work commutes, and business trips. In the absence of the Hiawatha Service, more than 85 percent of passengers would travel via alternative travel modes. Consequently, it is estimated that the Hiawatha Service removes nearly 400,000 vehicles and 32 million vehicle-miles (51 million vehicle-km) traveled from the congested Milwaukee-Chicago corridor annually. As the nation moves forward with significant investment in intercity passenger rail, there are lessons to be learned from the Hiawatha Service, both for rail service planning and the formation of transportation policy. For rail planning, this research indicates that the proper service configurations can result in a variety of trip purposes being accommodated on the route; this raises additional challenges when considering service elements such as on-board amenities. From a policy perspective, these findings present a compelling argument for continued investment in intercity passenger rail because they demonstrate that the availability of high-quality passenger rail service in the right corridor can have meaningful impacts on highway congestion, regional economic development and job access, and air quality and greenhouse gas emissions.
Sustainability in Track: A Precondition for High Speed Traffic
Authors: Veit Peter , Marschnig Stefan
Published: November 2010

Research and development concerning railways aim to either increase speed for passenger transport systems or to allow higher axle loads. Developments in the last decades show a big success, in heavy haul as well as in high speed operation. While track was practically destroyed by the high speed record run of 1955 (331 km/h respectively 205 mph) the high speed record 2007 with 574.8 km/h (360 mph) did not cause any track problems. In this time period track could be developed towards higher stability and preciseness due to the implementation of mechanized maintenance and the subsequent implementation of heavier track structures.
Railway Capacity Challenge: Measuring and Managing in Britain
Authors: Khadem-Sameni Melody , Preston John , Armstrong John
Published: November 2010

In the European Union, the total length of railway lines has decreased since 1970, mainly by abandoning very old routes such as those to coal mines. However, there has been huge growth in the transport of goods and passengers due to economic growth and globalization. Accommodating more passengers and goods on less infrastructure has resulted in the railway capacity challenge. The highest rate of growth in passenger kilometres in Europe belongs to Britain, where a rise of 42.2 percent has been achieved in the period 1995–2006 while the total length of railway lines has decreased from 19,330 route km in 1970 to 16,321 km in 2008. Railways originated from Great Britain therefore old tracks along with huge growth in railway transportation in recent years and inadequate infrastructure have resulted in a serious railway capacity challenge. This paper reviews different definitions of railway capacity, discusses issues for it (including having one degree of freedom for movement, constant need for maintenance due to wear caused by wheel-rail interaction and domino effect) and examines underlying infrastructure, traffic and operating parameters that affect capacity utilisation. Current methods for analyzing capacity utilisation are investigated: theoretical formulae, parametric and mathematical models and various simulation software. For tackling the capacity challenge, a hierarchy of soft and hard measures that can be deployed to increase capacity is proposed. Some of the latest initiatives in Britain to tackle railway capacity challenge and using the current infrastructure efficiently are analyzed including Network Modeling Framework (NMF), Delivering a Sustainable Railway, High Level Output Statement (HLOS) and Route Utilisation Strategies (RUSs). In the end, five policies that can contribute to better utilising capacity in Britain are suggested.
Development of an Unattended Track Geometry Measurement System
Authors: Scott Graham , Chillingworth Ema , Dick Matthew
Published: November 2010

Compliance with track standards and control of maintenance costs are critical aspects of the management of railroads. To facilitate this, track geometry measurement systems have evolved to allow monitoring of key track geometry parameters from moving trains. This paper describes how DeltaRail’s Trackline Two™ track geometry measurement system has been developed to overcome key technical shortcomings in existing systems. The resulting step change provides a cost-effective, robust, compact measurement system suitable for use on the broadest possible range of rail vehicles and networks, from a tram to a TGV. Extensive testing has demonstrated full compliance with appropriate standards. Significant improvements in reliability and repeatability of data have enabled DeltaRail to produce a modular system capable of sending data direct to value-adding analysis tools such as TrackMaster™ and VAMPIRE® so that track maintenance management can be optimized around train fleet and operational conditions. The system is easily operated in unattended mode allowing collection of track geometry data from in-service trains, increased frequency of data collection, and pointing the way for the track maintainers to realize significant value from integrated analysis and management options.
A Study on Cutting Temperatures of Turning Stainless Steel with Chamfered Main Cutting Edge Nose Radius Tools
Authors: Chang Chung-Shin
Published: November 2010

Temperatures of the carbide tip’s surface when turning stainless steel with a chamfered main cutting edge nose radius tool are investigated. The mounting of the carbide tip in the tool holder is ground to a nose radius as measured by a toolmaker microscope, and a new cutting temperature model developed from the variations in shear and friction plane areas occurring in tool nose situations are presented in this paper. The frictional forces and heat generated in the basic cutting tools are calculated using the measured cutting forces and the theoretical cutting analysis. The heat partition factor between the tip and chip is solved by the inverse heat transfer analysis, which utilizes the temperature on the P-type carbide tip’s surface measured by infrared as the input. The tip’s carbide surface temperature is determined by finite element analysis (FEA) and compared with temperatures obtained from experimental measurements. Good agreement demonstrates the accuracy of the proposed model.
A Novel Remote Controllable Drug Delivery System Triggered by Heating From Magnetic Nanoparticles
Authors: Wang Xiaoliang , Gu Hongchen , Zhu Xinyuan
Published: November 2010

Target drug delivery is one of the core issues in modern medicine. Although both thermo-sensitive and magnetic drug vehicles have been developed for this purpose, reliable drug targeting is yet to achieve, because it’s hard to control local temperature in body for thermo-sensitive drugs, and it’s also difficult to control the colloidal sizes of magnetic vehicles to meet the requirements for both long-time circulation and magnetic responsibility. Here we present a new technology to solve these two problems. The drug (taxel) was combined with hyper-branched thermo-sensitive polymer and magnetic nanoparticles. Magnetic responsibility of the complex can be remotely controlled by applying an alternating magnetic field. The untreated complexes were stable in dispersion, while after exposing to the alternating magnetic filed for 5 minutes, the complexes were destabilized and deposited from dispersion quickly. Unlike the commonly used water bath, the technology present here can heat up the drug vehicles remotely from outside, which must have great potentials in the applications of magnetic or thermo-sensitive drug delivery.
Experimental Study on Heat Transfer Characteristic of Plate Pulsating Heat Pipe
Authors: Quan Li , Jia Li
Published: November 2010

An experimental system of flat plate pulsating heat pipe was established and experimental research was carried out in this system to understand the mechanism of heat transfer and operating characteristics. The effects of start-up time, operating characteristics, and structures of passage, incline angle, fill ratio and working fluid on plate pulsating heat pipe were discussed. The results indicate that temperature of heating section decreases and the temperature of cooling section increases, then the thermal resistant of PHP is decreased once the plate pulsating heat pipe starts to work. Different start-up powers are needed for different fill ratios and incline angles. The inter pressure of PHP has some impacts on the start-up and operation of PHP. The pulsating heat pipes with different structures have different heat transfer performance. Increasing cross-sectional area and the number of turnings of the heat pipe can improve the heat transfer characteristics of heat pipes. Cross-section shape was also an important influencing factor. With the same cross-sectional area, heat pipe with triangular cross-section of the inner tubes gives better performance than that with rectangular cross-section.
Near-Field Radiative Transfer, Dispersion Forces, and Dyadic Green’s Functions
Authors: Narayanaswamy Arvind
Published: November 2010

Near–field force and energy exchange between two objects due to electrodynamic fluctuations give rise to dispersion forces such as Casimir and van der Waals forces, and thermal radiative transfer exceeding Plancks theory of blackbody radiation. The two phenomena dispersion forces and near–field enhancement of thermal radiation have common origins in the electromagnetic fluctuations. However, dispersion forces have contributions from quantum (zero–point) as well as thermal fluctuations whereas nearfield radiative transfer has contributions from thermal fluctuations alone. The forces are manifested through the Maxwell stress tensor of the electromagnetic field and radiative transfer through the Poynling vector. Both phenomena are elegantly described in terms of the Dyadic Greens function of the vector Helmholtz equation that governs the electromagnetic fields. In this talk, I will focus on the application of the Dyadic Greens function technique to near–field radiative transfer and dispersion forces. Despite the similarities, radiative transfer and forces have important differences that will be stressed on. I will end the talk with some open questions about the Dyadic Greens function formalism and its application to near–field radiative transfer.
Performance Simulations of a Gas Turbine Disk-Blade Assembly Employing Miniature Rotating Heat Pipes
Authors: Cao Yiding , Ling Jian
Published: November 2010

With a substantially increased gas inlet temperature in modern gas turbine engines, the cooling of turbine disks is becoming a challenging task. In order to reduce the temperature at the disk rim, a new turbine disk incorporating radially rotating heat pipes has been proposed. The objective of this paper is to conduct a numerical investigation for the cooling effectiveness of the rotating heat pipe. One of the major tasks of this paper is to compare the performance between a proposed disk-blade assembly incorporating radially heat pipes and a conventional disk-blade assembly without the heat pipes under the same heating and cooling conditions. The numerical investigation illustrates that the turbine disk cooling technique incorporating radially rotating heat pipes is feasible. The maximum temperature at the rim of the proposed disk can be reduced by more than 100°C in comparison with that of a conventional disk without heat pipes. However, the average temperature at the blade airfoil surface can be reduced by only about 10 degrees. Therefore, the results indicate that the average temperature of the airfoil surface is not very sensitive to the disk cooling condition. In addition, both the heat pipe length and diameter have an important effect on the turbine disk cooling. Under the permission of material strength, a longer heat pipe or a larger heat pipe will produce a lower temperature at the proposed disk rim.
A Molecular Dynamics Study on the Effects of Nanostructural Clearances on Thermal Resistance at a Liquid-Solid Interface
Authors: Shibahara Masahiko , Takeuchi Kiyoshi
Published: November 2010

The effects of the surface structures and the surface structural clearances at the nanometer scale on the thermal resistance at a liquid water-solid interface, as well as the dynamic behaviors of liquid molecules, were investigated directly by the classical molecular dynamics simulations. The thermal resistance between the solid wall and the liquid region was calculated by the temperature discontinuity at a liquid-solid interface and the energy flux that was added or subtracted by the Langevin method per unit area so as to maintain a constant solid wall temperature. When the potential parameter between liquid molecules and nanostructure atoms is equal to that between liquid molecules and solid wall atoms, the geometric surface area change depending on the nanostructures as well as their clearances and the dynamic behaviour change of the fluid molecules at the interface depending on the nanostructural clearances cause the thermal resistance reduction depending on the nanostructures at the liquid-solid interface. When the potential parameter between liquid molecules and nanostructure atoms is different from that between liquid molecules and solid wall atoms, the thermal resistance at the interface is dependent on the potential parameter between liquid molecules and nanostructure atoms rather than the geometric surface area in a molecular scale depending on the nanostructures as well as their clearances.
Cooling Behavior in a Novel Heat Sink Based on Muitilayer Staggered Honeycomb Structure
Authors: Liu Yonglu , Luo Xiaobing , Liu Wei
Published: November 2010

A novel heatsink based on a multilayer stack of thin metal plates with staggered honeycomb cells microchannels was investigated in this paper. A series of working-parametric tests such as different heat sink pipe diameter and pumping power were conducted for the microchannel cooling system to determine the heat transfer performance under small flow rate conditions. For the double fluid flow inlets and outlets heatsink design, experimental results showed that more uniform substrate temperature distribution was obtained than the single inlet and outlet ones. It showed that the heatsink design provided a good choice for electronic chips cooling applications.
The Characteristics of Heat Transfer and Flow on a Surface With Small Scale V-Shape Groove
Authors: Wang Jiansheng , Yang Zhiqin
Published: November 2010

The characteristics of heat transfer and flow in a rectangular channel with bottom of scale groove were investigated with numerical method. The numerical calculation was performed with large eddy simulation. A variety of small scale V-shapes groove with different of depth and space in longitudinal were employed in numerical simulation. The coherent structure near the surface of small scale groove was studied. The effect of the depth and space in longitudinal of small scale groove on coherent structure was investigated. Furthermore, the relationship between coherent structure and local heat transfer coefficient was investigated as well as. The numerical results indicate that the heat transfer performance of channel with small scale groove has been improved and the drag reduction has been gained in some case. The numerical simulation indicated that flow structure in different area of small scale groove had obvious difference and it would cause influence on local heat transfer coefficient.
Molecular Dynamics of Rupture Phenomenon in a Liquid Film on Nanowire Under Isothermal Condition
Authors: Shibata Atsushi , Ueno Ichiro
Published: November 2010

Dynamics of nano-meter-scale liquid film on nanowire is investigated through classical molecular dynamics simulation. Liquid film of argon with 12-6 Lennard-Jones potential on the solid surface with harmonic potential breaks up into several droplets in a relaxation process to make the total surface energy smaller. Instability emerged on the liquid film, its propagation along the wire, and pinching off of the nano-film are discussed. Theoretical investigations on this problem in a macroscopic-scale system have indicated that a liquid film on the wire of radius R will break up into drops if the axial wavelength of the surface perturbation λ > 2πR. If λ < 2πR, the film is stable. On a microscopic-scale, a similar phenomenon to a macroscopic system occurs. We simulate the liquid film with thickness e0 ≅ 1.5 nm on the solid cylinder. In addition, effect of wettability on instability concerned is examined by changing L-J potential parameter εINT.
Experimental Investigation of Fluid Flow and Internal Convection Heat Transfer in Mini/Micro Porous Media
Authors: Huang Yu-Li , Jiang Pei-Xue , Xu Rui-Na
Published: November 2010

The flow characteristics of different gases such as air, helium and carbon dioxide and internal convection heat transfer between the solid particles and the fluid in mini/micro porous media were studied experimentally. The test sections for fluid flow and heat transfer were made of sintered bronze particles with average diameters of 225 μm, 125 μm, 90 μm and 40 μm. The experimentally measured friction factors with consideration of compressibility for air, helium and carbon dioxide in the porous media with average diameters of 225 μm and 125 μm agree well with the known correlation for normal size porous media (the correlation of Aerov and Tojec), especially at the relatively high Reynolds numbers. The experimentally measured friction factors for air, helium and carbon dioxide in the porous media with average diameters of 90 μm are slightly less than the correlation of Aerov and Tojec at the relatively low Reynolds numbers. The experimental values for the friction factors for air, helium and carbon dioxide in the microporousmedia with 40 μm average diameters are much less than the correlation of Aerov and Tojec. The results show that rarefaction effects occur in air, helium and hydrogen flows in the microporous media with particle diameters less than 90 μm. The internal convection heat transfer coefficients between particles and fluid for air, helium and carbon dioxide in the micro porous media were determined experimentally.
Numerical Research of Roughness Effects on Flow and Heat Transfer Characteristics in Flat Microchannels
Authors: Yun Heming , Chen Baoming , Chen Binjian
Published: November 2010

Roughness effects on flow and heat transfer in flat microchannels has been numerically simulated by using CFD with fluid-solid conjugate heat transfer techniques, the surface roughness has been modeled through a series triangular toothed roughness cells. In this paper, the influence for roughness on the entrance length of flow and heat transfer has been emphasized, the influence for relative roughness on transitional Reynolds number has been also analyzed at the same time.
Simulation of Heat Transfer Around Nanoparticles
Authors: Barrat Jean-Louis , Merabia Samy , Joly Laurent , Vladkov Mihail
Published: November 2010

We present a short review of recent simulation work concerning heat transfer between nanoparticles and a suspending fluid. The role of numerical simulation in understanding such phenomena at a qualitative and quantitative level is emphasized. We discuss in particular the role of interfacial resistance, that of local curvature effects, and the possibility of achieving high temperatures inside the particles without creating a liquid vapor phase transition (boiling) in the surrounding fluid. Our present understanding on nanofluid conductivity from simulation studies is also discussed.
Green’s Function Solution of Dual-Phase-Lag Model
Authors: Lee Yung-Ming , Lin Pei-Chi , Tsai Tsung-Wen
Published: November 2010

In this study, the micro-scale heat conduction solution in a finite rigid slab computed with and without heat source is investigated. The analytical solution is derived by Laplace transform (LT) technique and Green’s function solution (GFS) method. The effect of heat source on the micro-scale heat conduction solution is also included in this paper. It is found that the temperature solution obtained by GFS method is smaller than that obtained by LT technique, and the GFS is in very good agreement with the solution obtained by the conventional Fourier’s law when τq = τT. Moreover, the temperature distributions computed by the LT technique are always overestimated in this study owing to the absence of the G2 effect. Hence, it is believed that the temperature solutions predicted by the GFS-LT method are more accurate than those evaluated by the LT technique. When time is increasing, the discrepancies of temperature solutions among various methods for τT > τq is increasing.
Microscopic Wetting at Microstructured Surface of Porous Silicon
Authors: Nagayama Gyoko , Ando Ryuji , Tsuruta Takaharu
Published: November 2010

Surface wettability is an important factor for micro/nanoscale thermal fluidic systems and it has attracted much interest for both fundamental research and practical applications. As one of the most attractive materials with controllable wettability, porous silicon is easy to be produced by the electrochemical etching. In this study, the effects of the microstructures of porous silicon on the wetting behavior of a pure water droplet were investigated experimentally. The solid-liquid contacting surface of the porous silicon substrate was prepared by varying both the geometrical microstructure and the chemical composition. The anodic etching was applied to the n type silicon substrate of orientation (100) and the geometrical microstructures of porous silicon were controlled by varying the fabrication conditions of the electrochemical etching. The pores of diameter ranging from 1–6 micrometers and the porosity up to 0.8 were obtained. Also, the surface chemical composition was controlled by coating the SiO2 layer or the CYTOP fluoropolymer layer directly on the porous silicon surface. The contact angle of the pure water droplet was measured at the prepared porous silicon surface in a room with constant temperature and humidity. The effects of the microstructures on the contact angle were discussed and the results were compared to both the classical theoretical models and a modified model based on the molecular dynamics simulations.
The Effect of Surface Treatment on the Drag Characteristics in Laminar Flow
Authors: Byon Chan , Nam Youngsuk , Kim Sung Jin , Ju Yongho Sungtaek
Published: November 2010

In this study, we explore the clear idea of drag change when the surface contains roughness. For that purpose, we performed a simple terminal velocity experiment using small solid spheres. The terminal velocity of Cu spheres is measured before and after they are surface treated to form superhydrophilic or superhydrophobic nanostructures and appreciable increase in the terminal velocity for both cases is observed. An analytic solution is derived to evaluate the corresponding slip length in an external flow and the result is comparable to values reported in previous studies of lithographically patterned superhydrophobic surfaces. To gain useful physical insight, incompressible Navier-Stokes equations are solved. From the solution, a simple explanation for the experimental observation is developed using the concept of friction drag and form drag. The total drag can be reduced when the reduction of the friction drag is larger than the increase of the form drag.
Heat Transport Characteristics of an Oscillating Heat Pipe With Al2O3 Nano-Fluid
Authors: Wang Shuangfeng , Lin Zirong , Zhang Weibao , Chen Jinjian , Tang Yong
Published: November 2010

Experimental investigation was conducted to exam the heat transport characteristics of an oscillating heat pipe (OHP) by using Al2O3 nano-fluid and pure water as working fluid. The test pipe consists of a copper tube with external diameter of 2.5 mm, inner diameter of 1.3 mm, and is welded into a four-turn oscillating heat pipe. The heat transport characteristics of the OHP have been studied under different liquid filling rates, different heat loads and different inclination angles (0° and 90°) when using water as working fluid. The results show that when heat load increases to a certain magnitude, the thermal resistance almost has little difference regardless of vertical bottom heat mode or horizontal heat mode. Comparing with pure water, Al2O3 nano-fluid as working fluid can enhance its heat-transport capability. When using vertical bottom heat mode and horizontal heat mode, the best concentration of Al2O3 nano-fluid is 0.5wt% and 0.1wt%, respectively.