Thermal runaway evolution of a 280 Ah lithium-ion battery with LiFePO_(4) as the cathode for different heat transfer modes constructed by mechanical abuse

Lithium iron phosphate batteries have been increasingly utilized in recent years because their higher safety performance can improve the increasing trend of recurring thermal runaway accidents.However,the safety performance and mechanism of high-capacity lithium iron phosphate batteries under internal short-circuit challenges remain to be explored.This work analyzes the thermal runaway evolution of high-capacity LiFePO_(4) batteries under different internal heat transfer modes,which are controlled by different penetration modes.Two penetration cases involving complete penetration and incomplete penetration were detected during the test,and two modes were performed incorporating nails that either remained or were removed after penetration to comprehensively reveal the thermal runaway mechanism.A theoretical model of microcircuits and internal heat conduction is also established.The results indicated three thermal runaway evolution processes for high-capacity batteries,which corresponded to the experimental results of thermal equilibrium,single thermal runaway,and two thermal runaway events.The difference in heat distribution in the three phenomena is determined based on the microstructure and material structure near the pinhole.By controlling the heat dissipation conditions,the time interval between two thermal runaway events can be delayed from 558 to 1417 s,accompanied by a decrease in the concentration of in-situ gas production during the second thermal runaway event.

Research on arc characteristics and metal transfer modes of ultrasonic assisted GMAW process

Ultrasonic assisted GMAW （U-GMAW） method is a novel process, which combines the ultrasonic wave with gas metal arc welding to improve the process stability and weld quality. The U-GMAW system is developed and the ultrasonic wave is applied by means of acoustic radiation. The arc characteristics and metal transfer modes are studied in comparison with conventional GMAW process. The arc plasma is compressed and the arc length is shorter than that in conventional GMAW process after the ultrasonic is applied onto the arc. The parameter range of short-circuiting mode is extended and the range of unstable transfer is minimized. The changes in arc characteristics are responsible for changes in metal transfer modes.

Computer-based sensing and visualizing of metal transfer mode in gas metal arc welding

Using Xenon lamp lights to overcome the strong interference from the welding arc, a computer-based system is developed to sense and visualize the metal transfer in GMAW. This system combines through-the-arc sensing of the welding current and arc voltage with high speed imaging of the metal transfer. It can simultaneously display the metal transfer processes and waveforms of electrical welding parameters in real-time The metal transfer videos and waveforms of electrical welding parameters can be recorded. Metal transfers under various welding conditions have been investigated with the system developed.

A comprehensive comparison on vibration and heat transfer of two elastic heat transfer tube bundles

Elastic heat transfer tube bundles are widely used in the field of flow-induced vibration heat transfer enhancement. Two types of mainly used tube bundles, the planar elastic tube bundle and the conical spiral tube bundle were comprehensively compared in the condition of the same shell side diameter. The natural mode characteristics, the effect of fluid-structure interaction, the stress distribution, the comprehensive heat transfer performance and the secondary fluid flow of the two elastic tube bundles were all concluded and compared. The results show that the natural frequency and the critical velocity of vibration buckling of the planar elastic tube bundle are larger than those of the conical spiral tube bundle, while the stress distribution and the comprehensive heat transfer performance of the conical spiral tube bundle are relatively better.

Digital television transmission based on asynchronous transfer mode

This paper introduces a method to realize digital television transmission based on asynchronous transfer mode (ATM), a technology based on fast packet switching. Choosing the integral multiple length of an ATM cell payload to equal to the length of an MPEG transport stream packet, an MPEG transport stream packet can be inextenso loaded by several ATM cells and trans-formed into ATM cells. Using ATM virtual connection technology and B-ISDN, the interoperability between ATM and DTV may be realized, and DTV signal transmission may also be realized finally.

Heat Transfer and Mode Transition for Laser Ablation Subjected to Supersonic Airflow

When laser ablation is subjected to supersonic flow, the influence mechanism of airflow on laser ablation behavior is still unclear. A coupled thermal-fluid-structure model is presented to investigate the influence of supersonic airflow on the development of a laser ablation pit. Results show that the aerodynamic convection cooling effect not only reduces the ablation velocity but also changes the symmetry morphology of the ablation pit due to the non-uniform convective heat transfer. Flow mode transition is also observed when the pit becomes deeper, and significant change in flow pattern and heat transfer behavior are found when the open mode is transformed into the closed mode.

Research on Asynchronous Transfer of DTV Video Signal

Digital TV (DTV) video signal transmission over ATM network is emphasized on.Some important problems are introduced about TV video signals asynchronous transfer to network application client, and the idea of video transfer design is discussed. The contents mainly include the DTV video streams asynchronous transfer topology, compressed coding adopted ATM network, asynchronous transfer efficiency and some problems of DTV video transmission in ATM network .

Development and preliminary study on the ultrasonic assisted GMAW method

The ultrasonic assisted GMAW （U-GMAW） method is proposed to achieve a more stable welding process and better weld quality. Tbe U-GMA W system is dereloped, which consists of power supplies, ultrasonic vibration system and specially designed u＇elding torch. The U-GMA W process and eonventional GMA W process are compared through bead-on-plate welding. The weld beads arc continuous and well protected, while the weld surface appearances by GMA W and U-GMA W are apparently diffierent. The metal transfe ,node changes from globular transfer to short-circuiting transfer after ultrasonic wave is applied onto the arc.

STF:PROVIDE RATE GUARANTEES IN INPUT-QUEUED SWITCH

A QoS-aware input-queued scheduling algorithm, called Smallest Timestamp First (STF), is proposed, which is improved upon iSLIP and can allocate bandwidth among inputs sharing a common output based on their reservation by assigning suitable finishing tiniest-amps to contending cells. STF can also provide isolation between flows that share a common output, link. Misbehaving flows will be restricted to guarantee the behaving flows' bandwidth. Simulations prove the feasibility of our algorithm.

Hardware-in-the-loop simulation of communication networks

To enhance the fidelity and accuracy of the simulation of communication networks,hardware-in-the-loop（HITL） simulation was employed.HITL simulation methods was classified into three categories,of which the merits and shortages were compared.Combing system-in-the-loop（SITL） simulation principle with high level architecture（HLA）,an HITL simulation model of asynchronous transfer mode（ATM） network was constructed.The throughput and end-to-end delay of all-digital simulation and HITL simulation was analyzed,which showed that HITL simulation was more reliable and effectively improved the simulation credibility of communication network.Meanwhile,HLA-SITL method was fast and easy to achieve and low-cost during design lifecycle.Thus,it was a feasible way to research and analyze the large-scale network.

异步传输模式网络设计自愈研究

在ATM网络设计中,自愈是指网络发生故障时,在不需要人工干预的情况下,就能很快恢复维持服务连贯性。这包括两个方面:网络计划和运作,其中网络计划包括最佳/接近最佳网络设计,网络运作利用分配冗余信道来处理恢复机制。网络的自愈能力可以用存储率(restoration ratio)来反映,这里采用聚集存储率(aggregate restoration ratio),研究的目的是为了比较基于通路和链接恢复网络自愈能力的不同,以及不同设计因素对自愈能力的影响。

Buffer management optimization strategy for satellite ATM

ECFD （erroneous cell tail drop）, a buffer management optimization strategy is suggested which can improve the utilization of buffer resources in satellite ATM （asynchronous transfer mode） networks. The strategy, in which erroneous cells caused by satellite channel and the following cells that belong to the same PDU （protocol data Unit） are discarded, concerns non-real-time data services that use higher layer protocol for retransmission. Based on EPD （early packet drop） policy, mathematical models are established with and without ECTD. The numerical results show that ECTD would optimize buffer management and improve effective throughput （goodput）, and the increment of goodput is relative to the CER （cell error ratio） and the PDU length. The higher their values are, the greater the increment. For example, when the average PDU length values are 30 and 90, the improvement of goodput are respectively about 4% and 10%.

A COMBINED ADMISSION CONTROL ALGORITHM WITH DA PROTOCOL FOR SATELLITE ATM NETWORKS

Admission control is an important strategy for Quality of Service (QoS) provisioning in Asynchro- nous Transfer Mode (ATM) networks. Based on a control-theory model of resources on-Demand Allocation (DA) protocol, the paper studies the effect of the protocol on the statistical characteristics of network traffic, and proposes a combined connection admission control algorithm with the DA protocol to achieve full utiliza- tion of link resources in satellite communication systems. The proposed algorithm is based on the cross-layer-design approach. Theoretical analysis and system simulation results show that the proposed algo- rithm can admit more connections within certain admission thresholds than one that does not take into account the DA protocol. Thus, the proposed algorithm can increase admission ratio of traffic sources for satellite ATM networks and improve satellite link utilization.

MODELING OF THE PRIORITY SCHEDULING INPUT-LINE GROUP OUTPUT WITH MULTI-CHANNEL IN ATM EXCHANGE SYSTEM

In this paper, an extended Kendall model for the priority scheduling input-line group output with multi-channel in Asynchronous Transfer Mode （ATM） exchange system is proposed and then the mean method is used to model mathematically the non-typical non-anticipative PRiority service （PR） model. Compared with the typical and non-anticipative PR model, it expresses the characteristics of the priority scheduling input-line group output with multi-channel in ATM exchange system. The simulation experiment shows that this model can improve the HOL block and the performance of input-queued ATM switch network dramatically. This model has a better developing prospect in ATM exchange system.

Temperature distribution of fluids in a two-section two-phase closed thermosyphon wellbore

Compared with a conventional single section two-phase closed thermosyphon （TPCT） wellbore, a two-section TPCT wellbore has better heat transfer performance, which may improve the temperature distribution of fluid in wellbores, increase the temperature of fluid in wellheads and even more effectively reduce the failure rate of conventional TPCT wellbores. Heat transfer performance of two-section TPCT wellbores is affected by working medium, combination mode and oil flow rate. Different working media are introduced into the upper and lower TPCTs, which may achieve a better match between the working medium and the temperature field in the wellbores. Interdependence exists between the combination mode and the flow rate of the oil, which affects the heat transfer performance of a two-section TPCT wellbore. The experimental results show that a two-section TPCT wellbore, with equal upper and lower TPCTs respectively filled with Freon and methanol, has the best heat transfer performance when the oil flow rate is 200 L/h.

The Application of NPs in WCDMA Systems

Recent efforts to add new services to the wide-band code division multiple accesses （WCDMA） system have increased interest in network processor （NP）-based routers that are easy to extend and evolve. In this paper, an application of NPs in routing engine module （REM） of radio network controller （RNC） in WCDMA system is proposed. The measuring results show that NPs have good performance and efficiency in routing traffic of the communication network and the simulation verifies the fast forwarding function of NPs.

English Immersion in China as a Case of Educational Transfer

The English immersion program in China is a case of educational mode transfer from foreign language immersion in North America.This article analyzes the process of the transfer from the perspective of comparative education,using the model of“four stages of educational borrowing.”First,it revisits the recent research on educational transfer and briefly introduces the model.Then,it highlights the stages of English immersion program transfer in China.Finally,it concludes that the transfer initiated actively by innovative Chinese scholars,occurs at local and micro levels,with structural context factors and supra-national and sub-national actors playing significant roles in the process.It argues that the model may be applicable in analyzing other educational modes with some adaptations when necessary.

Discrete particle simulations of bubble-to-emulsion phase mass transfer in single-bubble fluidized beds

A classical Euler-Lagrangian model for gas-solid flows was extended with gas component mass conser- vation equations and used to obtain fundamental insights into bubble-to-emulsion phase mass transfer in bubbling gas-solid fluidized beds. Simulations of injected single rising bubbles under incipient fiuidiza- tion conditions were carried out, using Geldart-A and -B particles. Phenomena observed in the simulations and those of various theoretical models used to derive phenomenological models were compared to chal- lenge the assumptions underlying the phenomenological models. The bubble-to-emulsion phase mass transfer coefficients calculated for the simulations using Geldart-B particles were in a good agreement with predictions made using the Davidson and Harrison （1963） model. The bubble-to-emulsion phase mass transfer coefficients for Geldart-A particles were, however, much smaller than the predictions obtained from theoretical models （e.g. Chiba and Kobayashi （1970））. The newly developed model allows a detailed analysis of various hydrodynamic aspects and their effects on the mass transfer characteristics in and around rising bubbles in fluidized beds.

A Study of Broadband Intelligent Network Implementing Video Conference and Multicast Routing Algorithm

The dissertation studies the architecture of broadband intelligent network (BIN) and implementation of video conference based on ATM network and of multicast routing problem on video conference using BIN under the aid of the important task Study of IN and B ISDN Integration (69896244) sponsored by National Natural Science Fund. A lot of points of view and solutions are present. The main contributions in the dissertation are as follows:\; (1) Design the new architecture of BIN and improve the architecture of BIN proposed by ITU T. It is easy to set up the connections of video conference using the new architecture of BIN.\; (2) Present the detailed scheme that BIN controls and implements video conference without specialized resource function, study the scheme of all the media on video conference transmitted and switched under the control of BIN, and discuss how to implement point to multipoint communications using BIN.\; (3) First present the scheme of implementing multicast routing algorithms on video conference using BIN.\; (4) Explicitly introduce a series of concepts including neighboring node, neighboring node set, neighboring edge, then propose an Adjustable Dynamic Multicast (ADM) routing algorithm which is suitable for video conference, analyze its performances, and prove the algorithm is appropriate and feasible.\; (5) Develop a degree constrained dynamic multicast (DADM) routing algorithm which can find less cost multicast routing tree. The results of simulation and experiments confirm that DADM algorithm can find the less cost multicast tree. Finally, analyze the relation between the size of degree constrained and value of multicast tree cost.\; (6) Present a delay constrained dynamic multicast routing algorithm suitable for video conference characteristic, and advise a series of schemes reducing the delay of transmitting all the media on videoconference.\; (7) First propose implementing the reliable multicast routing transport protocol using BIN, thereby ACK implosion problem can be solved. The protocol only requires finite memory and is scalable.

Simulation of the Tree Algorthm in ATM Networks

This paper proposes an algorithm for multicast routing in ATMnetworks. We define the network cost of a routing as the combinationof the cost. If establishing connections, the cost of the overallbandwidth and overall switchings, our routing algorithm works on theoriginal topology of ATM networks with physical switches and physi-cal links, and different switching functionalities of VirtualPath(VP)switches and Virtual Channel(VC)switches in the network. Itgenerates an optimal multicast routing with the minimal overallnetwork cost. Simulations with MATLAB have been made to compare thequality of the routing generated by our algorithm with those of othertwo Major algorithms.