化学成分及退火温度对镀锡板调质度的影响

采用50kg真空炉及模拟退火炉进行冶炼和退火试验,结合硬度、拉伸试验及金相分析,研究了镀锡原板中的w(C)和退火温度对调质度的影响。结果表明,在相同的退火温度条件下,随着镀锡原板中w(C)增加约0.001%,镀锡板的洛氏表面硬度值(HR30Tm)增加约5,其强度增加5～10 MPa,而伸长率下降约1.5%;在w(C)不变的条件下,随着退火温度的上升,镀锡板的洛氏表面硬度值下降。

罩式炉退火T4级上限硬度镀锡原板生产工艺优化

通过对罩式炉退火制度进行优化 ,采用优化的辊面凸度曲线 ,在双机平整机上 ,使厚度小于 0 2 5mm镀锡原板的干平整伸长率大于 1 3%。利用退火制度和平整伸长率的合理组合 ,生产优质T4级上限硬度镀锡原板。首先在实验室条件下进行了模拟实验 ,试轧后投入批量生产。结果表明 ,镀锡原板的表面硬度达到HR30T6 3～ 6 5 ,板形良好 ,各项性能要求均满足用户需求。

不同轧制和退火方式对冷轧钢板耐蚀性的影响

冷轧板的退火制度和平整(调质)的程度是影响其性能的重要因素。为了研究不同轧制和退火方式对冷轧钢板耐蚀性的影响,采用开路电位-时间曲线与Tafel曲线测试考察了不同退火方式、调质度与冷轧方式冷轧低碳钢板的耐蚀性,并采用SEM,AFM,金相显微镜与XRD测试方法研究了钢板的表面形貌、轧制纹深度、粗糙度、晶粒尺寸以及结晶取向等特性,并分析了这些特性对耐蚀性的影响。结果表明:与连续退火钢板相比,经罩式退火后表面轧制纹少且浅,粗糙度低,晶粒大,晶界少,非金属夹杂物少,(211)晶面取向度大,因而其耐蚀性强;一次冷轧钢板连续退火后的调质度由T-3到T-5,硬度增大,轧制纹增多且加深,晶粒尺寸减小且均匀性下降,非金属夹杂物增多,(211)晶面取向度下降,耐蚀性随之下降;连续退火二次冷轧DR-8钢板的轧制纹多且深,表面粗糙度大,晶粒尺寸小且不均匀,在6种板材中其耐蚀性最差。

Modeling and performance evaluation of QoS-aware job scheduling of computational grids

To achieve high quality of service （QoS） on computational grids, the QoS-aware job scheduling is investigated for a hierarchical decentralized grid architecture that consists of multilevel schedulers. An integrated QoS-aware job dispatching policy is proposed, which correlates priorities of incoming jobs used for job selecting at the local scheduler of the grid node with the job dispatching policies at the global scheduler for computational grids. The stochastic high-level Petri net （SHLPN） model of a two-level hierarchy computational grid architecture is presented, and a model refinement is made to reduce the complexity of the model solution. A performance analysis technique based on the SHLPN is proposed to investigate the QoS-aware job scheduling policy. Numerical results show that the QoS-aware job dispatching policy outperforms the QoS-unaware job dispatching policy in balancing the high-priority jobs, and thus enables priority-based QoS.

INVESTIGATION ON HARDENED STEEL MILLING WITH MICRO-END MILL

Tool wear and breakage of the micro-milling tool is an important problem for high speed machining of hardened steel die and mould. Dry milling of S136 hardened steel is carried out using TiAlN coated carbide micro-end mill (2 mm).The effect of cutting speed, feed per tooth and radial depth of cut on cutting force is analyzed. Cutting parameters adapting to dry machining and strategy optimized for higher rate of material removal with lower cutting force are attained. Results of SEM observation show that the main failure patterns of micro-end mill are breakage of tool tip, wear and drop-off of surface coating, micro-chipping, and breakage of flank.

Analysis on Dam-Breaking Mode of Tangjiashan Barrier Dam in Beichuan County

Tangjiashan landslide is a typical high-speed consequent landslide of medium-steep dip angle. This landslide triggered by earthquake took place in about semi-minute. The relative sliding displacement is 900 meters, so average sliding speed is about 30 meters per second. The longitudinal length of barrier dam which is formed by high-speed landslide along river is 803.4 meters; and maximum width crossing river is 611.8 meters. And its volume is estimated about 20.37 million steres. Through detailed geological investigation of the barrier dam, together with early geological information before earthquake, geological structures of the barrier dam and its stability of upstream and downstream slopes are studied when water level reaches different elevations in condition of continual after shocks with seismic intensity of 7 or 8 Richter scale. On this basis, dam-breaking mode of barrier dam is discussed deeply. Thereby, analytic results provide significant guidance and advices to front headquarters of Tangjiashan barrier dam, so that some proper engineering measures can be implemented and flood discharge can be carried out well.

A NEW SCHEDULING ALGORITHM TO PROVIDE PROPORTIONAL QOS IN OPTICAL BURST SWITCHING NETWORKS

A new scheduling algorithm, which aims to provide proportional and controllable QoS (Quality of Service) in terms of burst loss probability for OBS (Optical Burst Switching) networks, is proposed on the ba- sis of a survey of QoS schemes in current OBS networks. With simulations, performance analysis and com- parisons are carried out in detail. The results show that, in the proposed scheme, burst loss probabilities are proportional to the given factors and the control of QoS performance can be achieved with better performance. This scheme will be beneficial to the OBS network management and the tariff policy making.

A QoS-Aware Packet Scheduling Mechanism in Cognitive Radio Networks for Smart Grid Applications

Cognitive radio sensor network is applied to facilitate network monitoring and management, and achieves high spectrum efficiencies in smart grid. However, the conventional traffic scheduling mechanisms are hard to provide guaranteed quality of service for the secondary users. It is because that they ignore the influence of diverse transition requirements in heterogeneous traffi c. Therefore, a novel Qo S-aware packet scheduling mechanism is proposed to improve transmission quality for secondary users. In this mechanism, a Qo S-based prioritization model is established to address data classification firstly. And then, channel quality and the effect of channel switch are integrated into priority-based packet scheduling mechanism. At last, the simulation is implemented with MATLAB and OPNET. The results show that the proposed scheduling mechanism improves the transmission quality of high-priority secondary users and increase the whole system utilization by 10%.

Limnological instrumentation in the middle of the 19^(th) century:the first temperature and density profiles measured in the Dead Sea

The first modem survey of the Dead Sea was performed by the Geological Survey of Israel in 1959-1960, and the report published remains the baseline study for our understanding of the physical and chemical properties of the lake. At the time the Dead Sea was a meromictic lake with a strong salinity gradient separating the deep waters （〉40 m depth） from the less saline surface waters. A few results of analyses of deeper water samples collected in the 1930s were reported, but overall we have very little information about the structure of the lake＇s water column before the 1959-1960 survey. However, it is little known that data on the physical and the chemical structure of the Dead Sea water column were obtained already in the middle of the 19~ century, and the information collected then is highly relevant for the reconstruction of the limnological properties of the lake in earlier times. The expedition of Lieutenant William Lynch （U.S. Navy） in 1848 reported the presence of a temperature minimum at a depth of-18 m, and also retrieved a water sample collected close to the bottom for chemical analysis. In 1864, the French Dead Sea exploration by the Duc de Luynes and his crew yielded detailed density and salinity profiles for a number of sampling stations. The results of these pioneering studies are discussed here, as well as the sampling equipment and measuring instruments used by the 1848 and the 1864 expeditions.

QoE-Aware Proportional Fair Scheduling for Multiuser Multiservice Wireless Networks

The effective radio resource allocation al-gorithms, which satisfy diversiform requirements of mobile naltimedia services in wireless cellular net-works, have recently attracted more and more at-tention. This paper proposes a service-aware scheduling algorithm, in which the Mean Opinion Score （MOS） is chosen as the unified metric of the Quality of Experience （QoE）. As the network needs to provide satisfactory services to all the users, the fairness of QoE should be considered. The Propor- tional Fair （PF） principle is adopted to achieve the trade-off between the network perfonmnce and us- er fairness. Then, an integer progranming problem is formed and the QoE-aware PF scheduling princi-ple is derived by solving the relaxed problem. Simu-lation results show that the proposed scheduling principle can perform better in terms of user fair-ness than the previous principle maximizing the sum of MOS. It also outperfoms the max-rain scheduling principle in terms of average MOS.

Effects of Nitrogen-controlled Atmosphere Storage on the Quality of Ordinary Late Japonica Rice

Nitrogen-controlled atmosphere has been internationally recognized as a green grain storage technology.This study used Jiangsu ordinary late japonica rice as the test material and investigated the effects of different nitrogen concentrations(88%,93%,and 98%)and different storage temperatures(10,20,and 30℃)on the rice quality indexes during nitrogen-controlled atmosphere storage.The results showed that the water content of rice in different nitrogen-controlled atmosphere groups fluctuated between 12.85%~13.15%at 20℃,which was significantly lower than that in the control group.High-concentration nitrogen-controlled atmosphere treatment(93%and 98%)effectively slowed down the fatty acid value,malondialdehyde(MDA)content,and electrical conductivity of rice,and also significantly inhibited the rapid increase in the final viscosity and water absorption of rice starch,while the changes in the peak viscosity and attenuation value of rice were not significantly different from those of the control group.Meanwhile,the impacts of controlled atmosphere storage with 98%nitrogen concentration on the water content,fatty acid value,MDA content,electrical conductivity,gelatinization characteristics,and water absorption of rice at 10,20,and 30℃were studied.It was found that all quality parameters,except the MDA content,changed most gently at 10℃.In conclusion,the combined treatment of nitrogen-controlled atmosphere storage(98%)and low temperature(10℃)can effectively delay the quality deterioration of ordinary late japonica rice.

AN EFFICIENT SCHEDULING ALGORITHM FOR INPUT-QUEUED SWITCHES

This letter presents an efficient scheduling algorithm DTRR (Dual-Threshold Round Robin) for input-queued switches. In DTRR, a new matched input and output by round robin in a cell time will be locked by two self-adaptive thresholds whenever the queue length or the wait-time of the head cell in the corresponding Virtual Output Queue (VOQ) exceeds the thresholds. The locked input and output will be matched directly in the succeeding cell time until they are unlocked. By employing queue length and wait-time thresholds which are updated every cell time simultane- ously, DTRR achieves a good tradeoff between the performance and hardware complexity. Simula- tion results indicate that the delay performance of DTRR is competitive compared to other typical scheduling algorithms under various traffic patterns especially under diagonal traffic.

Improving Playback Quality of Peer-to-Peer Live Streaming Systems by Joint Scheduling and Distributed Hash Table Based Compensation

In Peer-to-Peer(P2P) streaming systems,video data may be lost since peers can join and leave the overlay network randomly,thereby deteriorating the video playback quality.In this paper we propose a new hybrid mesh and Distributed Hash Table(DHT) based P2P streaming system,called HQMedia,to provide high playback quality to users by maintaining high data dissemination resilience with a low overhead.In HQMedia,peers are classified into Super Peers(SP) and Common Peers(CP) according to their online time.SPs and CPs form a mesh structure,while SPs alone form a new Streaming DHT(SDHT) structure.In this hybrid architecture,we propose a joint scheduling and compensation mechanism.If any frames cannot be obtained during the scheduling phase,an SDHT-based compensation mechanism is invoked for retrieving the missing frames near the playback point.We evaluate the performance of HQMedia by both theoretical analysis and intensive simulation experiments on large-scale networks to demonstrate the effectiveness and scalability of the proposed system.Numerical results show that HQMedia significantly outperforms existing mesh-based and treebased P2P live streaming systems by improving playback quality with only less than 1% extra maintenance overhead.

Questionnaire Research on Indoor Environment Quality i n China

With 1 185 pi eces of questionnaire, it is found that in China, people take fresh air, odor, e tc., as well as indoor air temperature, humidity, as the most important indoor a ir parameters. It is also found that there is a significant sensitivity differen ce in indoor environment between southerners and northerners in China. People fr om different regions have different demands for their working and living environ ment. Therefore, as a good design of air conditioning system, it is strongly rec ommended that the different demands of people from different regions should be t aken into consideration.

Survey on Gamasyab River Water Quality in Nahavand Township, Iran

Gamasyab River, which is the biggest river of Hamadan Province, is sourced from Karstic Springs in Nahavand Township Southern Mountainous Region and supplies a major part of water needs of the region. In this research seasonal variation of water quality and also the degree of pollution related to Gamasyab River water have been assessed. First the general status of the river was studied and four sampling stations were determined. In this research, the quality of river water including Dissolved Oxygen （DO）, five days Biochemical Oxygen Demand （BOD）5, Chemical Oxygen Demand （COD）, Nitrate, phosphate, temperature, Total Hardness（TH）, Total Suspended Solid （TSS）, Total Dissolved Solid （TDS） and PH have been determined and assessed on a monthly basis within a five years period. The results were reported as seasonally and presented using statistical tables and graphs. These results showed that Nitrate concentration in Gamasyab River is strongly depending on distance from Gamasyab spring. By increasing the distance from Gamasyab spring, nitrate concentration increased. The amount of DO in the river water is stable in each station within the year. Air temperature changes have had no effect in the amount of DO. Therefore, it is recommended that the river pollution control plans be implemented more serious than before, non point source pollution related to agricultural activities be managed and prevent from pouring untreated rural wastewaters to the mentioned river.

A routing algorithm for industrial wireless network based on ISA100.11a

ISA100.11 a industrial wireless network standard is based on a deterministic scheduling mechanism.For the timeslot delay caused by deterministic scheduling,a routing algorithm is presented for industrial environments.According to timeslot,superframe,links,channel and data retransmission of deterministic scheduling mechanisms that affect the design of the routing algorithm,the algorithm selects the link quality,timeslot delay and retransmission delay as the routing criteria and finds the optimum communication path by k shortest paths algorithm.Theoretical analysis and experimental verification show that the optimal paths selected by the algorithm not only have high link quality and low retransmission delay,but also meet the requirements of the deterministic scheduling.The algorithm can effectively solve the problem of packet loss and transmission delay during data transmission,and provide a valuable solution for efficient data transmission based on determinacy.

Changes in Plasma Osmolality, Cortisol and Amino Acid Levels of Tongue Sole(Cynoglossus semilaevis) at Different Salinities

A serial of salinity transferring treatments were performed to investigate the osmoregulation of tongue sole(Cynoglossus semilaevis). Juvenile tongue sole were directly transferred from a salinity of 30 to 0, 10, 20, 30, 40 and 50. Blood sampling was performed for each treatment after 0, 1, 6 and 12 h, as well as after 1, 2, 4, 8, 16 and 32 d. The plasma osmolality, cortisol and free amino acids were assessed. Under the experimental conditions, no fish died after acute salinity transfer. The plasma cortisol level increased 1 h after the abrupt transfer from a salinity of 30 to that of 0, 40 and 50, and decreased from 6 h to 8 d after transfer. Similar trends were observed in the changes of plasma osmolality. The plasma free amino acids concentration showed a ‘U-shaped' relationship with salinity after being transferred to different salinities for 4 days. More obvious changes of plasma free amino acid concentration occurred under hyper-osmotic conditions than under hypo-osmotic conditions. The concentrations of valine, isoleucine, lysine, glutamic acid, glycine, proline and taurine increased with rising salinity. The plasma levels of threonine, leucine, arginine, serine, and alanine showed a ‘U-shaped' relationship with salinity. The results of this study suggested that free amino acids might have important effects on osmotic acclimation in tongue sole.

Effect of Modified Atmosphere Packaging on Postharvest Quality of Barangan Banana

An experiment retail film packaging system was used to compare the atmospheric composition within sealed packs containing barangan banana fruits. This research was done in order to study the effect of packaging films with different permeability properties on the physicochemicalproperties of barangan banana during storage at room temperature （28 ± 2 °C） and at 15 °C. The films used were 0.09 mm low density polyethylene （LDPE）, 0.04 mm polypropylene and 0.057 mm LDPE compared with unwrapped fruits as control. Barangan bananas were evaluated each 5 days intervals for changes in moisture content, total sugars, vitamin C, hardness and color. Unwrapped barangan bananas were overripe and soft after 15 days at both temperature conditions. Sealed packages especially using LDPE at 15 °C delayed the development of the yellow color of banana until 20 days of storage and had the lowest weight loss.

Tunable Self-assembled Weak Polyelectrolyte Brushes

The authors have investigated the pH and ionic strength response of self-assembled layers formed by adsorption of amphiphilic weak polyelectrolytes. Using the SFA （Surface Forces Apparatus） the authors measured force-distance profiles of poly （isoprene）-poly （acrylic acid） block copolymers adsorbed on mica. Also by Atomic Force Microscopy the authors captured single polyelectrolyte molecule adsorbed on a surface. The effect of salt concentration （Cs） and pH upon the height of the brush layers was explored mainly by measuring the forces between two adsorbed polyelectrolyte brushes. At pH = 4 our results are in good agreement with the scaling prediction L0 ∝Cs-1/3 Changing the pH from 4 to 10 causes a remarkable swelling of the polymer layer, but only a weak dependence on salt concentration was detected at the higher pH. This can be attributed to the degree of dissociation, which depends on the local pH value. At low pH the polyelectrolyte chains have a low charge density, while on increasing the pH the degree of dissociation rises, and the increased charge density is followed by swelling of the adsorbed layer. The local concentration of ions in the brush is now greater than that of pH = 4 and approximately equivalent to 0.3 M. So the swelling is only weakly dependent on salt concentration in the range 0.01-1.0 M. The results demonstrate the tunable nature of such self-assembled polyelectroiyte brushes whose height and range of interactions, can be systematically controlled by adjusting the pH and ionic strength of the medium.

Sustainability Issues Related to the Engineering Geology of Long Linear Developments

The development of long linear structures such as roads, rail roads, tunnels, canals and pipelines often has unique engineering geology challenges. These include geological modeling, the identification of material strength and support factors, stability and risk issues, material excavation characteristics and the proposal of techniques for overcoming geotechnical problems, which are normally assessed as part of the conventional engineering geological investigation. An additional factor that is becoming increasingly important but is seldom included in investigations is the sustainability of the geotechnical inputs, in contrast to the sustainability of the project which is generally included. Sustainability issues revolve around the non-renewable nature of most construction resources and there is no doubt that the injudicious use of these construction materials and construction water is not sustainable in the long term: it is thus essential that the engineering geo-logical investigation should take cognizance of such issues and be adapted to provide the design engineer with the information that will maximize the sustainability options. This will also require a closer on-going relation-ship between the engineering geologist and the design engineer. This paper highlights significant sustainability issues (note that these differ from conventional environmental issues) and suggests some mitigating solutions. The sustainability issues discussed include primarily material and water usage, with some reference to energy conservation (mostly through alternative material usage and processing techniques and transportation).