临钢中板2300mm轧机综合测试及分析

通过对临钢中板2300mm轧机的综合测定,了解该设备的实际负荷情况及有关工艺参数。由此经过工艺制度的修订,为扩大轧制规格与品种,设备潜能的发挥提供科学依据。

Nondestructive evaluation of mechanical properties of nanostructured Al-Cu alloy at room and elevated temperatures

The influence of processing variables on the mechanical properties of a nanostructured Al-10 wt.%Cu alloy was investigated.Stress-strain microprobe®system(SSM)and its automated ball indentation®(ABI®)test were used for evaluating the mechanical properties of this alloy.The tests were conducted at 21℃ on the bulk samples that were mechanically alloyed for 6 h at two ball-to-powder mass ratios(BPR)of 30:1 and 90:1.Furthermore,the tests were conducted at 200 and 400℃ on the samples that were processed at BPR of 90:1.Increasing BPR resulted in raising the final indentation load from(316±26)to(631±9)N and reducing the final indentation depth from 111 to 103μm.Regarding the samples that were processed at BPR of 90:1,increasing the test temperature from 21 to 400℃ resulted in decreasing the final load from(631±9)to(125±1)N and increasing the final depth from 103 to(116±1)μm.The sample processed at BPR of 90:1 and tested at 21℃ revealed the highest strength and the least deformability while the sample processed at BPR of 90:1 and tested at 400℃ exhibited the lowest strength and the greatest deformability,as compared to all samples under study.

Rules for confidence intervals of permeability coefficients for water flow in over-broken rock mass

Based on the steady-state seepage method, we used the Mechanical Testing and Simulation 815.02 System and a self-designed seepage instrument for over-broken stone to measure seepage properties of water flows in three types of crushed rock samples. Three methods of confidence interval in describing permeability coefficients are presented: the secure interval, the calculated interval and the systemic interval. The lower bound of the secure interval can be applied to water-inrush and the upper bound can solve the problem of connectivity. For the calculated interval, as the axial pressure increases, the length of confidence interval is shortened and the upper and lower bounds are reduced. For the systemic interval, the length of its confidence interval, as well as the upper and lower bounds, clearly vary under low axial pressure but are fairly similar under high axial pressure. These three methods provide useful information and references for analyzing the permeability coefficient of over-broken rock.

Effects of pre-precipitation of Cr_2N on microstructures and properties of high nitrogen stainless steel

Aging precipitation and solid solution heat treatment were carried out on three steels which have chromium content of 18%, manganese content of 12%, 15%, 18%, and nitrogen content of 0.43%, 0.53%, 0.67%, respectively. The mechanisms of precipitation and solid solution of high nitrogen anstenitic stainless steel were studied using the scanning electron microscopy, transmission electron microscopy, electron probe micro analysis and mechanical testing. The results show that, Cr2N is the primary precipitate in the tested stainless steels instead of Cr23C6. Cr2N nucleates at austenitic grain boundaries and grows towards inner grains with a lameUar morphology. By means of pre-precipitation of Cr2N at 800 ~C, the microstructure of the steels at solid solution state can be refined, thus improving the strength and plasticity. After the proposed treatment, the tensile strength, the proof strength and the elongation of the tested steel reach 881 MPa, 542 MPa and 54%, respectively.

Thermo-plasticity of high-strength and high-ductility 7050 aluminum ingot

Thermo-plasticity of homogenized 7050 aluminum ingot was investigated by instantaneous tensile tests conducted at different temperatures. The results show that, with the increase of testing temperatures, the strength decreases, and the plasticity increases firstly and then decreases in homogenized 7050 ingot. When the studied alloy is deformed between 380℃ and 420℃, the deformation resistance is lower and plasticity is better. And the actual heating temperature for ingot before hot extrusion should be controlled between 360 ~C and 400 ~C. At low tensile temperatures, the deformation structure is mainly composed of dislocation substructure. With the increase of testing temperatures, transgranular fracture transforms into intergranular fracture progressively during deformation. At high tensile temperatures, the grain boundaries are weakened, deformation is concentrated at the grain boundaries and the re-orientation of equilibrium phases at grain boundaries appears.

Can Artificial Climate Trends in Global Reanalysis be Reduced by Dynamical Downscaling:A Case Study of China

In this study, the ability of dynamical downscaling for reduction of artificial climate trends in global reanalysis is tested in China. Dynamical downscaling is performed using a 60-km horizontal resolution Regional Integrated Environmental Model System （RIEMS） forced by the NCEP-Department of Energy （DOE） reanalysis II （NCEP-2）. The results show that this regional climate model （RCM） can not only produce dynamically consis- tent fine scale fields of atmosphere and land surface in the regional domain, but it also has the ability to minimize artificial climate trends existing in the global reanalysis to a certain extent. As compared to the observed 2-meter temperature anomaly averaged across China, our model can simulate the observed inter-annual variation and variability as well as reduce artificial climate trends in the reanalysis by approximately 0.10℃ decade-1 from 1980 to 2007. The RIEMS can effectively reduce artificial trends in global reanalysis for areas in western China, especially for regions with high altitude mountains and deserts, as well as introduce some new spurious changes in other local regions. The model simulations overesti- mated observed winter trends for most areas in eastern China with the exception of the Tibetan Plateau, and it greatly overestimated observed summer trends in the Si- chuan Basin located in southwest China. This implies that the dynamical downscaling of RCM for long-term trends has certain seasonal and regional dependencies due to imperfect physical processes and parameterizations.

Microstructure and fracture behavior of SiO_2 glass ceramic and TC4 alloy joint brazed with TiZrNiCu alloy

Vacuum brazing of SiO2 glass ceramic and TC4 alloy using a commercially available TiZrNiCu foil was investigated. The interfacial microstructure and the fractures were examined with an optical microscope （OM） and an S-4700 scanning electron microscope （SEM） equipped with an energy dispersive spectrometer （EDS） and an electron probe X-ray microanalyzer （EPMA）. The structure of joint interface was identified by XRD （JDX-3530M）. Meanwhile, the fracture paths of the joints were comprehensively studied. The results show that processing parameters, especially the brazing temperature, have a significant effect on the microstructure and mechanical properties of joints. The typical interface structure is SiO2/Ti2O＋Zr3Si2＋Ti5Si3/（Ti,Zr）＋Ti2O＋ TiZrNiCu/Ti（s.s）/TiZrNiCu＋Ti（s.s）＋Ti2（Cu,Ni）/TC4 from SiO2 glass ceramic to TC4 alloy side. Based on the mechanical property tests, the joints brazed at 880 ℃ for 5 rain has the maximum shear strength of 23 MPa.

Effects of Rhodiola rosea supplementation on mental performance,physical capacity,and oxidative stress biomarkers in healthy men

Purpose： The objective of this study was to investigate the effects of chronic Rhodiola rosea （R. rosea） supplementation on mental and physical performance, as well as hormonal and oxidative stress biomarkers. Methods： Twenty-six healthy male students received either R. rosea extract （600 mg/day; RR） or placebo （PL） in a randomized double-blind trial. Prior to supplementation （Term I） and following 4 weeks of supplementation （Term II）, the students underwent psychomotor tests for simple and choice reaction time, included in the Vienna Test System. Also, the subjects performed VO2peak test. Blood samples were obtained before and after the test to measure the hormonal profile （cortisol, testosterone, and growth hormone）, as well as the biomarkers of oxidative stress （lipid hydroperoxides, total antioxidant capacity, and superoxide dismutase） and muscle damage （creatine kinase）. Results： R. rosea ingestion shortened reaction time and total response time. Moreover, a greater relative increase in the number of correct responses was observed in RR group as compared to the PL group. No changes in endurance exercise capacity and hormonal profile were observed after R. rosea ingestion. R. rosea ingestion raised plasma total antioxidant capacity. It did not, however, affect other measured parameters. Conclusion： Chronic R. rosea ingestion does not affect physical performance, but can improve the results of some psychomotor tests （simple and choice reaction time） in young, healthy, and physically active men. The improvements in mental performance, however, at least in our study, seem not to be related to changes in cortisol release or antioxidant activity of R. rosea extract. Thus, the specific mechanisms responsible for these effects still need to be elucidated.2018 Published by Elsevier B.V. on behalf of Shanghai University of Sport. This is an open access article under the CC BY-NC-ND license. （http：//creativecommons.org/licenses/by-nc-nd/4.0/）.

Hydrophilic characteristics of soft rock in deep mines

A series of water absorption tests on dried soft rock have been conducted by the intelligent testing system for water absorption tests in deep soft rock, including tests of water absorption with and without pres- sure. The results show that the water absorbing capacity of rock with a certain pressure is larger than that of rock without pressure： however, the relationship between the water absorbing percentage and the time can be expressed by w（t） = a（l - e^-bt）. In hi-logarithmic coordinates, the hydrophilic relationship with time in tests with pressure could be characterized by linearity, while they present concave or convex in tests without pressure. Based on the hypothesis that each influential factor is irrelevant and they have a linear correlation with the water absorbing capacity, we calculated the weight coefficient of each factor according to experimental results under different conditions. The calculations demonstrate that the effec- tive porosity, content of smectite and kaolinite are all positively correlated with the water absorption capacity of rock; meanwhile, the fractal dimension of the effective pores presents a negative correlation with the water absorption capacity of rock. The water absorption capacity with pressure increases with increasing illite, chlorite and chlorite/smectite formation and a decrease in illite/smectite formation and the fractal dimension of the effective pores, while it is opposite in tests without pressure. The weight coefficient of smectite is smallest among positive factors, and the fractal dimension of the effective pores is the smallest amongst the negative factors.

Study on the resistance spot welding technology of 22MnMoB hot stamping quenched steel

In this paper, the spot welding technology of a new kind of 22MnMoB hot stamping quenched steel sheet was systematically studied by power frequency spot welder. Through a series of technology and test experiments, we have obtained the optimal spot welding technological parameter condition. According to the results, the relations among spot welding technological parameter, welding nugget, mechanical property and fracture mode were discussed. The effects of all the welding parameters such as welding current, welding time and electrode force on the quality of joint can be boiled down to one thing--the diameter of welding nugget. The experimental results showed that welding nugget diameter determines the mechanical property of spot welding joint and the relation between welding nugget diameter and the mechanical property of joint presents a kind of linear mathematic representation. There are two typical fracture models of 22MnMoB hot stamping quenched steel sheet, i.e., interracial fracture and nugget pullout. Other than mild steel or normal high strength steel, in the shearing tensile test, hot stamping quenched steel has a great tendency to fail in interfacial mode due to the effects of high strength matrix structure, welding soft zone and the porosity level of fusion zone.

Plastic deformation behavior of Mg97Zn1Y2 extruded alloys

The mechanical properties of the Mg97ZnlY2 extruded alloy containing the long-period stacking ordered phase, the so-called LPSO-phase, with a volume fraction of 24%-25%, were examined by compression tests and cyclic tension-compression deformation tests. The plastic behavior of the extruded alloys with compositions of Mg99.2Zn0.2Y0.6 and Mg89Zn4Y7 （molar fraction, %）, which were almost the same compositions of Mg matrix phase and LPSO phase in Mg97Zn1Y2 Mg/LPSO two-phase alloy, respectively, were also prepared. By comparing their mechanical properties, the strengthening mechanisms operating in the Mg97Zn1 Y2 extruded alloy were discussed. Existence of the LPSO-phase strongly enhanced the refinement of Mg matrix grain size during extrusion, which led to a large increment of the strength of alloy. In addition, the LPSO-phases, which were aligned along the extrusion direction in Mg97Zn1Y2 extruded alloy, acted as hardening phases, just like reinforced fibers.

The Effect of Background Knowledge on EFL Learners＇ Reading Comprehension

Schema is known to play an important role in reading comprehension. The schema embodying the learners background knowledge of cultural familiar materials facilitates the understanding of the text （Pritchard, 1990）. Also Steffensen, Joag-Dev, and Anderson （1979） and Nelson （1987） proposed that the schemata embodying background knowledge influenced how well the text would be comprehended. However, Hudson （1982） and Carrell （1984） found there was no significant background effect in advanced level learners. From those studies, it seems that background effect is different at different language proficiency levels. Thus, the present study examines the interaction between background knowledge and language proficiency in reading comprehension. The participants were freshmen of National Chiayi University. They were divided into three language proficiency levels based on the General English Proficiency Test. Four reading comprehension tests were constructed to assess their reading comprehension： cultural familiar/unfamiliar text and topic familiar/unfamiliar text. The results of this study showed that participants had better performance on the culture/topic familiar text than the culture/topic unfamiliar text. Thus the findings suggest that the teacher can use teaching activities, such as pre-reading activities or vocabulary teaching to increase the background knowledge when teaching readings to EFL （English as a foreign language） learners

The Use of Task-Based Activities to Improve Listening and Speaking Skills in EFL Context

The aim of this study was to improve EFL learners＇ English listening and speaking skills at a State University in Turkey, School of Foreign Languages, Department of Basic English B1 and BI＋ groups through task-based activities. The participants were 56 in total, studying in the academic year of 2014-2015 Spring Fall. The instruments used for collecting data were 16 lesson plans and the speaking and listening quiz results as post-tests. The data were statistically analyzed by mean, max, and min values of the scores. Teaching process and the lesson plans were recorded by researcher then presented in essay form. After the implementation and the post-tests, the participants＇ opinions about the task were collected as an interview. The results of the study showed that B1 groups did not get significant results from listening test and get nearly significant scores from speaking test while the listening and speaking results of BI＋ groups through task-based learning after the implementations were highly significant, which shows that their participation in the task-based activities in the classroom reflected the results positively. Also the students＇ opinions about task-based learning and teaching activities were respectively positive. As a result, it can be said that task-based activities play a significant role in improving listening and speaking skills in EFL settings.

An Empirical Study of Listening Comprehension Strategies in Autonomous Learning Environment

This is a report on an empirical study of listening comprehension strategies in autonomous learning environment which was conducted among the second-year non-English majors in Shandong University （Weihai） on the basis of O＇Malley and Chamot＇s theory of learning strategies, dating from September, 2010 to January, 2011. The study aims to verify the teachability of listening comprehension strategies, the enhancement of students＇ awareness of applying these strategies in their listening comprehension pratice and positive effects of listening comprehension strategies cast on students＇ listening comprehension proficiency. Questionnares on listening comprehension strategies were conducted at the beginning and at the end of the research respectively, in addition to the listening comprehension strategies training from the beginning to the end of the research. Besides, there was a interview arranged in the middle of the research. Meanwhile, there were two listening comprehension proficiency tests arranged at the beginning and at the end of the research. According to the results, it can be indicated that the students＇ strategy awareness can be promoted, while their listening proficiency also can be improved by the listening comprehension strategy training.

Effects of sintering temperature on microstructure and performance of Ti-based Ti-Mn alloy anodic material

A novel Ti-based Ti-Mn composite anode used for electrolytic manganese dioxide(EMD) fabrication was developed by a two-step heating manganizing technique.The effects of sintering temperature on the manganized microstructure and the performance of the composite anode were studied by scanning electron microscopy(SEM),mechanical properties tests at room temperature and electrochemical methods.The results show that the thickness of the diffusion layer increases with the increase of sintering temperature up to 1 100 °C;whereas,the surface Mn content increases and reaches the maximum at 1 000 °C and then decreases thereafter.Lower surface Mn content is beneficial for the enhanced corrosion resistance and lowered open cell voltage in electrolytic process.The new anode prepared under the optimized conditions has been applied in industry and exhibits superior economic benefits to conventional Ti anodic materials.

ESP Needs Analysis： A Case Study of PEH Students, University of Khartoum

Needs analysis is considered a necessary first step in designing ESP courses. This study, therefore, aims at analysing students at the Faculty of Public and Environmental Health （PEH） at the University of Khartoum （U of K）, Sudan, needs for English language. The study adopted the needs analysis framework suggested by Dudley-Evans and St John （1998） focusing on target needs analysis, present situation analysis, and learning means needs analysis. The study used a questionnaire, a proficiency test, and an interview to collect data. The participants were 490 students at PEH （390 participated in the questionnaire and 100 in the proficiency test） and two professors at the Faculty. The study found that PEH students need English language for academic study. The students rated their proficiency as good, but the test revealed that they were of weak proficiency. All the four skills in addition to vocabulary, grammar, and pronunciation are regarded as important to the students. Similarly, almost all the sub-skills are found to be important. The students have a variety of leaming needs such as learning in pairs, groups, and through ICT. The study recommends that PEH students＇ proficiency should be raised and a course that meets the students＇ needs is needed.

Proficiency Testing in Analysis of Wine Products

The quality variety wines which are produced in specified regions of Slovakia are mostly watched category of wine in European Union. Quality of the measurement for appropriate parameter in wine sample is given by uncertainty. Therefore, protocol of analysis has to have an uncertainty of measurement and should be made in accredited laboratory. In Slovakia, there are six wine growing regions （Tokaj, east Slovakia region, south Slovakia region, middle Slovakia region, Nitriansky region and Little-Carpathian region） where the quality wines with protected designation of origin are produced. Central Controlling and Testing Institute in Agriculture in Bratislava is a state organization, which has an accredited laboratory for testing wine products before introduction into the market. This article presents the results of the authors＇ measurements in proficiency testing FAPAS （food analysis performance assessment scheme） which were organized by Central Science Laboratory in York （England） in 2011. The authors add also interlaboratory comparison in 2012 between Slovak accredited laboratories. The results show very good agreement. Quality control in the wine sector presents very important feature in the market, therefore, using certified reference materials and checking the accredited laboratories with interlaboratory comparisons is very helpful. Testing of wine in the authors＇ laboratory is performed by EN ISO/IEC： 17025. The results show that z-score lies not outside the range ±2 and this is a chance that the authors＇ results are actually acceptable.

Local Path Planning Method of the Self-propelled Model Based on Reinforcement Learning in Complex Conditions

Conducting hydrodynamic and physical motion simulation tests using a large-scale self-propelled model under actual wave conditions is an important means for researching environmental adaptability of ships. During the navigation test of the self-propelled model, the complex environment including various port facilities, navigation facilities, and the ships nearby must be considered carefully, because in this dense environment the impact of sea waves and winds on the model is particularly significant. In order to improve the security of the self-propelled model, this paper introduces the Q learning based on reinforcement learning combined with chaotic ideas for the model＇s collision avoidance, in order to improve the reliability of the local path planning. Simulation and sea test results show that this algorithm is a better solution for collision avoidance of the self navigation model under the interference of sea winds and waves with good adaptability.

All-solid-state microscopic interferometer with frequency-variation and phase-shifting capability

A novel microscopic interferometry with ability of frequency-variation and phase-shifting is proposed for microstructures testing. By using acousto-optic technique, sequential carriers can be generated with different spatial frequencies so that the temporal phase unwrapping method can be applied for decoding the height information. Combined with phase-shifting technique realized by spatial light modulator, this method is especially suitable for interferometric measurement with high precision and large dynamic range.

Guidance of CET Translation Test for College English Teaching Reform

English teaching reform are launched nationwide, involving curriculum, classroom teaching as well as many other aspects of language proficiency test. Its purpose is to change the past neglect of English proficiency training. Newly created translation project in CET will play a huge role in promoting direction on the teaching reform and further clarify the core teaching reform.