Multi-objective optimization of rolling schedule based on cost function for tandem cold mill

In terms of tandem cold mill productivity and product quality, a multi-objective optimization model of rolling schedule based on cost fimction was proposed to determine the stand reductions, inter-stand tensions and rolling speeds for a specified product. The proposed schedule optimization model consists of several single cost fi.mctions, which take rolling force, motor power, inter-stand tension and stand reduction into consideration. The cost function, which can evaluate how far the rolling parameters are from the ideal values, was minimized using the Nelder-Mead simplex method. The proposed rolling schedule optimization method has been applied successfully to the 5-stand tandem cold mill in Tangsteel, and the results from a case study show that the proposed method is superior to those based on empirical formulae.

Synthesis and properties of SrFe_(12)O_(19) obtained by solid waste recycling of oily cold rolling mill sludge

The aim of this study was to develop a new approach for the preparation of environmentally friendly, high-value products from oily cold rolling mill(CRM) sludge. Utilizing oily CRM sludge as a source of iron, strontium hexaferrite(SrFe_(12)O_(19)) powders were prepared by multi-step processes involving acid leaching, chemical conversion treatment, and synthesis by a citrate precursor. The influences of citric acid dosage and the pH of the sol system on the formation, crystallite size, and magnetic properties of the obtained SrFe_(12)O_(19) powders were investigated. High saturation magnetization(74.8 mA·m^2·g^(–1)) and intrinsic coercivities(614.46 mT) were achieved for pH 7.0 of the sol system, for which the molar ratio of citric acid dosage to the total dosage of Fe^(3+) and Sr^(2+) was 1.5. This study presents a new approach to utilizing oily CRM sludge, and even refractory iron-containing solid waste.

Anti-interference Strategy of 20-Hi Cold Mill Automatic Gauge Control

Automatic gauge control(AGC in the article)is the key technology of product thickness accuracy and flatness quality in modern cold rolling mill.Most traditional AGC control algorithms need stable external system conditions and hard to stabilize under complex interference that meets coverage requirements.This paper presents a new anti-interference strategy for AGC control of 20-Hi cold reversing mill.The proposed algorithm introduces a united dynamic weights algorithm of feed forward-mass flow to avoid the complex interference problem in AGC control,the relevant control strategy is provided to eliminate the adverse effects.At the same time,the D-value between feed forward-mass flow pre-computation and thickness measurement deviation is dynamic compared,the final gap position regulation is calculated by developing a set of united dynamic weights between feed forward control and mass flow control.Finally,the output of controllers is sent to actuator though a constant rate smoothing.The proposed strategy is compared with conventional AGC control on Experimental platform and project application,the results show that the proposed strategy is more stable than comparison method and majority of system uncertainty produced by mentioned interference is significantly eliminated.

Dynamic matrix predictive control for a hydraulic looper system in hot strip mills

Controlling the looper height and strip tension is important in hot strip mills because these variables affect both the strip quality and strip threading. Many researchers have proposed and applied a variety of control schemes for this problem, but the increasingly strict market demand for strip quality requires further improvements. This work describes a dynamic matrix predictive control(DMC) strategy that realizes the optimal control of a hydraulic looper multivariable system. Simulation experiments for a traditional controller and the proposed DMC controller were conducted using MATLAB/Simulink software. The simulation results show that both controllers acquire good control effects with model matching. However, when the model is mismatched, the traditional controller produces an overshoot of 32.4% and a rising time of up to 2120.2 ms, which is unacceptable in a hydraulic looper system. The DMC controller restricts the overshoot to less than 0.08%, and the rising time is less than 48.6 ms in all cases.

Research on Single-Side Long Edge of Hot Rolled Strip Caused by Asymmetrical Stiffness of Mill Stand

To analyze and solve the problem of single-side long edge of hot rolled strip in certain domestic factory, the asymmetrical deformation of rolls and strip in asymmetrical stiffness mill stand based on slit beam model, the strip profile and rolling force distribution at the exit of asymmetric stiffness stand mill were calculated using influence function method. Considering the character of in-site equipment and technology, a scheme of adjusting load distribution in finishing mill was made and the experiment was applied. Comparison of strip profile between new load distribution and the old one shows that the method can solve single-side long edge problem well.

Strip Thickness Control of Cold Rolling Mill with Roll Eccentricity Compensation by Using Fuzzy Neural Network

In rolling mill, the accuracy and quality of the strip exit thickness are very important factors. To realize high accuracy in the strip exit thickness, the Automatic Gauge Control (AGC) system is used. Because of roll eccentricity in backup rolls, the exit thickness deviates periodically. In this paper, we design PI controller in outer loop for the strip exit thickness while PD controller is used in inner loop for the work roll actuator position. Also, in order to reduce the periodic thickness deviation, we propose roll eccentricity compensation by using Fuzzy Neural Network with online tuning. Simulink model for the overall system has been implemented using MATLAB/SIMULINK software. The simulation results show the effectiveness of the proposed control.

An Adaptive Model and Algorithm for an Electro-hydraulic Position Servo System in Auto Gauge Control for Aluminum Hot Tandem Mill

The electro-hydraulic servo position control system(HPC) is the core of an auto gap control for a modern four-high continuous hot strip mill.The actuators are loaded with considerable external disturbances,rolling forces,and the system stiffness and position accuracy will become hypersensitive to the leakage and the compressibility of the oil.Many efforts have being made to increase the position accuracies.The conventional resources are proportion-integral-differential(PID) controller.But the PID controller is faint for a considerable external disturbance.In this paper,by introducing the adaptive control strategy of model reference the reciprocities of the system structure with the loads were analyzed.With the Lyapunov energy function,an adaptive control algorithm applied to improve the system accuracy was formulated.The system simulations and the selection of parameters of the model were also discussed.The simulations show the static state errors at 0.02%.Finally,the industrial experimental result was given.

Slip Line Field Solution for Second Pass in Lubricated 4-High Reversing Cold Rolling Sheet Mill

The development of a possible slip line field (slf) for theoretical calculations of the deforming pressure (load) in a second pass of a lubricated cold rolling sheet mill and validation using values from an aluminium sheet rolling mill was done in this work. This will be relevant in the manufacturing industries providing an easy method for determining necessary applied rolling load. Experimental rolling was carried out to observe the shear lines in the deformation field. Construction of possible slip line field model was developed adhering strictly to assumptions of rigid plastic model. Calculation of the deforming force/load was achieved using Hencky’s equation. Results showed that the load calculations for constructed slip line field using aluminium sheet rolling as an example tallied with values obtained from Tower Aluminium rolling mill. Slip line fields constructed for the second pass described adequately the rolling pressure in the cold rolling process, giving a valid solution of the exact load estimates on comparison with the industrial load values. Roll pressure along the arc of contact rose fairly linearly from the entrance to a maximum at the exit point. This work showed that slf for the first pass in a cold rolling mill cannot be used for subsequent passes;it requires construction of slfs for each pass in the cold rolling process.

The Theoretically Studies and Field Testing of Self-Insulation Exterior Wall in the Hot Summer and Cold Winter Zone

The energy efficiency design of the exterior wall in the buildings of the hot summer and cold winter zone of China should consider the heat prevention in summer and the heat insulation in winter. The self-insulation of the exterior?wall is a more feasible design to satisfy the energy efficiency of buildings in the?zone. However, the systematic research is urgently needed for the self-insulation of the exterior wall in the hot summer and cold winter zone of China. The paper tested the thermal performance of the common non-clay materials such as shale sintered hollow brick, sand autoclaved aerated concrete block, etc. by means of indoor experiments. The energy efficiency effect of the common materials was verified using dynamic calculation soft PKPM and several constitutions of exterior wall with different main bricks and insulation materials on the heat bridge were simulated, too. Besides, the tests of the thermal performance of exterior wall in real constructions were carried out to testify the practical effect of the recommended constitutions of exterior wall with different main bricks and insulation materials on the heat bridge. The conclusions are: the physical and thermal properties of the six non-clay wall material are better than the clay porous brick;the thermal performance of the non-clay brick can be improved obviously through the rational arrangement of the holes;shale sintered hollow brick after increasing the holes and rationalizing the hole arrangement and sand autoclaved aerated concrete block are recommended for buildings in the hot summer and cold winter area of China. The dynamic calculation results show that the thermal performances?of the non-clay materials are all satisfied with the energy efficiency;The heat transfer coefficient of the exterior wall with composition?③,?in which?the main wall was sand autoclaved aerated concrete block and the material on the heat bridge was sand autoclaved aerated concrete plate, is the smallest among the three recommended compositions.

Two stages power generation test of the hot dry rock exploration and production demonstration project in the Gonghe Basin,northeastern Qinghai-Tibet plateau,China

The Hot Dry Rock(HDR)is considered as a clean and renewable energy,poised to significantly contribute to the global energy decarbonization agenda.Many HDR projects worldwide have accumulated valuable experience in efficient drilling and completion,reservoir construction,and fracture simulation.In 2019,China Geological Survey(CGS)initiated a demonstration project of HDR exploration and production in the Gonghe Basin,aiming to overcome the setbacks faced by HDR projects.Over the ensuing four years,the Gonghe HDR project achieved the first power generation in 2021,followed by the second power generation test in 2022.After establishing the primary well group in the initial phase,two directional wells and one branch well were drilled.Noteworthy progress was made in successfully constructing the targeted reservoir,realizing inter-well connectivity,power generation and grid connection,implementing of the real-time micro-seismic monitoring.A closed-loop technical validation of the HDR exploration and production was completed.However,many technical challenges remain in the process of HDR industrialization,such as reservoir fracture network characterization,efficient drilling and completion,multiple fracturing treatment,continuous injection and production,as well as mitigation of induced seismicity and numerical simulation technology.

Land Suitability Evaluation of Zanthoxylum schinifolium in Dry and Hot Valley of Jinsha River: A Case Study of Jiaopingdu Town of Luquan Yi and Miao Autonomous County,Yunnan Province

According to the recent practice in Laopingzi Village,Jiaopingdu Town,Luquan Yi and Miao Autonomous County(Luquan County hereinafter)in dry and hot valley of Jinsha River,the development of Zanthoxylum schinifolium Sieb.et Zucc planting industry can help farmers gradually get rid of poverty and achieve a virtuous cycle of ecological environment.It is a sustainable poverty alleviation way.Based on the three aspects of soil properties,climatic conditions,and topographical conditions influencing the growth of Z.schinifolium,this paper selected eight evaluation factors to establish a suitability evaluation system for Z.schinifolium,used the analytic hierarchy process to determine the indicator,and determined the weight of the evaluation indicators.Besides,it calculated the comprehensive suitability index of land suitability of Z.schinifolium and evaluated the suitability of Z.schinifolium land in Jiaopingdu Town of Luquan County.The results showed that the suitable area for the cultivation of Z.schinifolium in Jiaopingdu Town reached 7270.78 ha,accounting for 88.69%of the study area;the area of unsuitable land was 922.07 ha,accounting for 11.31%of the study area.Among the suitable land areas,the high suitability area reached562.99 ha,accounting for 7.79%;the moderate suitability area was 2206.76 ha,accounting for 28.61%;the low suitability area was4599.03 ha,accounting for 63.6%.Based on the results of suitability evaluation,it came up with pertinent recommendations for the development of Z.schinifolium industry in Jiaopingdu Town.

THE COLD AND HOT DAMAGES TO THE CITRUS IN THE THREE GORGES AREA OF THE CHANGJIANG RIVER

Starting from the research on and collection of the damaging factors andindex of the cold and hot damages to citrus, this peper systematically studies the apparent properties in temporal and spatial distribution, differences, relationship of the twokinds of disasters and their impact on citrus production in the Three Gorges area inHubei. It also reveals the important faCt that it is warmer in winter and hotter in springsince the 1980s, which is the cause of departing to two poles of the cold and hot damages, and discusses the alleviating effect to the disasters by the Three Gorges Project.Finally some countermeasures are proposed.

Suitability and Construction of Self-Insulation Walls in the Hot Summer and Cold Winter Zone of Southern Shaanxi

In this paper, the suitability and construction technology of self-insulation walls were studied under the specific climatic conditions and regional resources of Hanzhong and Ankang in the hot summer and cold winter zone of Southern Shaanxi. Through the calculation of heat transfer coefficient and thermal inertia index, combined with the specifications of the shale hollow brick and aerated concrete block of Hanzhong and Ankang in southern Shaanxi, the thermal performance and suitable thickness of the external wall using self-insulation materials that meet the Design Standard for Energy Efficiency of Residential Buildings(DBJ61-65-2011) in Shaanxi Province were obtained. The results showed that the self-insulation wall had technical suitability in the hot summer and cold winter zone. The research results provide not only a theoretical basis for the external wall insulation design of urban residential buildings in the hot summer and cold winter zone of southern Shaanxi, but also a reference for designers to carry out energy-saving design of external walls of residential buildings in other similar climate zones.

Augmenting the Heat Sink for Better Heat Dissipation

Heat sinks were invented to absorb heat from an electronic circuit conduct, and then to dissipate or radiate this heat to the surrounding supposedly, ventilated space, at a rate equal to or faster than that of its buildup. Ventilation was not initially recognized as an essential factor to thermal dispersion. However, as electronic circuit-boards continued to heat up, circuit failure became a problem, forcing the inclusion of miniaturized high speed fans. Later, heat sinks with fins and quiet fans were incorporated in most manufactured circuits. Now heat sinks come in the form of a fan with fans made to function as fins to disperse heat. Heat sinks absorb and radiate excess heat from circuit-boards in order to prolong the circuit’s life span. The higher the thermal conductivity of the material used the more efficient and effective the heat sink is. This paper is an attempt to theoretically design a heat sink with a temperature gradient lower than that of the circuit board’s excess heat.

DECOUPLED MODEL FOR FLATNESS CONTROL IN 4-H CVC COLD ROLLING MILLS

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｐｒｅｃｉｓｅｃｏｎｔｒｏｌｏｆｒｏｌｇａｐｉｎ４ｈＣＶＣｍｉｌｓｉｓｐａｒｔｉｃｕｌａｒｌｙｄｉｆｉｃｕｌｔｄｕｅｔｏｔｈｅｃｏｍｐｌｅｘｉｎｔｅｒａｃｔｉｏｎｓｂｅｔｗｅｎｗｏｒｋｒｏｌｓｈｉｆｔｉｎｇａｎｄｂｅｎ...

Ballistic performance of titanium-based layered composites made using blended elemental powder metallurgy and hot isostatic pressing

Metal matrix composites tiles based on Ti-6Al-4V(Ti64)alloy,reinforced with 10,20,and 40(vol%)of either TiC or TiB particles were made using press-and-sinter blended elemental powder metallurgy(BEPM)and then bonded together into 3-layer laminated plates using hot isostatic pressing(HIP).The laminates were ballistically tested and demonstrated superior performance.The microstructure and properties of the laminates were analyzed to determine the effect of the BEPM and HIP processing on the ballistic properties of the layered plates.The effect of porosity in sintered composites on further diffusion bonding of the plates during HIP is analyzed to understand the bonding features at the interfaces between different adjacent layers in the laminate.Exceptional ballistic performance of fabricated structures was explained by a significant reduction in the residual porosity of the BEPM products by their additional processing using HIP,which provides an unprecedented increase in the hardness of the layered composites.It is argued that the combination of the used two technologies,BEPM and HIP is principally complimentary for the materials in question with the abilities to solve the essential problems of each used individually.

Verification of Hazard Analysis and Critical Control Point in Hotels and Catering Units: Evaluation of the Cleaning and Disinfection Procedures and Microbiological Monitoring of Hot and Cold Meals

The aim of the present study is to assess the efficacy of the methods used in a HACCP system by measuring the Total Viable Count (TVC) and Coliforms, after cleaning and disinfecting the surfaces used and also by monitoring TVC and enterobacteriaceae of hot and cold meals. In order to evaluate the appropriateness of the surfaces used, samples were obtained from kitchens of 37 Greek hotels/resorts, all of which operated a documented HACCP safety management scheme, while the samples of hot and cold meals were selected from the menu of a catering unit and collected from the actual point of hot and cold dishes banquette at the start time (time 0) and after 4 hours. The developed colonies were counted. The results showed that only 13.5% of the hotels presented surfaces without any TVC or coliforms and 86.5% of the hotels had surfaces with TVC or coliforms or both above the limits. However, 75.8% of the total surfaces examined were acceptable for TVC and 81.9% of the surfaces examined were coliforms. Our microbiological monitoring of food showed that the TVC content of hot meal samples after 4 hours of display (above 60℃) was not significantly different from the TVC content of the aforementioned samples at time 0, while in cold meals TVC and enterobacteriaceae content had significantly risen after 4 hours of display (below 5℃).Conclusively, insufficient application of disinfection and ineffective surface and equipment cleaning programs were found. Additionally, cold meals are more vulnerable than hot meals in developing TVC and enterobacteriaceae.

Mechanical and wear properties of Al-Al_3Mg_2 nanocomposites prepared by mechanical milling and hot pressing

β-A13Mg2 intermetallic was used as a reinforcing agent to improve the mechanical properties of an aluminum matrix. Different amounts of A13Mg2 nanoparticles （ranging from 0wt% to 20wt%） were milled with aluminum powders in a planetary ball mill for 10 h. Consolidation was conducted by uniaxial pressing at 400β under a pressure of 600 MPa for 2 h. Microstructural characterization confirms the uniform distribution of A13Mg2 nanoparticles within the matrix. The effects of nano-sized A13Mg2 content on the wear and mechanical properties of the composites were also investigated. The results show that as the A13Mg2 content increases to higher levels, the hardness, compressive strength, and wear resistance of the nanocomposites increase significantly, whereas the relative density and ductility decrease. Scanning electron microscopy （SEM） analysis of worn surfaces reveals that a transition in wear mechanisms occurs from delamination to abrasive wear by the addition of A13Mg2 nanoparticles to the matrix.

桑天牛卵长尾啮小蜂的繁殖生物学研究

The reproduction characteristics of Aprostocetus prolixus, which is a new parasitioid on Apriona germarii, were studied. It demonstrated that the female adult can generate offspring by either sex reproduction or parthenogenesis, but all the offspring were male if they were from the mode of parthenogenesis. The sex ratio, with investigating in nature, was 2.38∶1. The environmental conditions had notable influence on sex ratio, survival ratio and fecundity. Its sex ratio increased to 3.48∶1 by feeding complementary nutrition that adding with 20% honey. The temperature has great effect on Aprostocetus prolixus in terms of system research, of which adult longevity decreased with temperature from 17.5 ℃ to 35 ℃ and its ability of reproduction increased between 25 ℃ and 30 ℃ but the acme at 27.5 ℃. Without the feeding complementary nutrition, on the other hand, the female adult will both lose the ability of fecundity at the temperature below 17.5 ℃ and over 35 ℃. With humidity increasing from 40% to 80%, its fecundity increased significantly. It also showed that there was no significant influence of temperature on fecundity between the 4 ℃ to 8 ℃ when cold storage( i.e. the matured larvae for 90 d, the adults for 10 d and the host egg for 40 d).

HOTO工具箱系列设计,工具也要美美的

来源:https://www.red-dot.org/zh/project/hoto-toolbox-series-63470HOTO工具箱系列产品颜值在线、布局合理、携带方便。它极简优雅的外观设计,打破了人们心中对传统工具笨重、不美观的刻板印象,甚至让人丝毫看不出这是存放电动工具的产品。HOTO工具箱系列的外观以浅色为主,设计简约、线条柔和,边缘圆润。实用的提手和开合扣与整体设计融为一体,方便携带。极具设计美感的外观让它可与任何现代生活环境和谐地融为一体,无需像其他电动工具那样,只能放在储藏室或杂物间里。传统的工具箱一般都配有大量功能复杂的小工具,而HOTO系列则只提供了专为家庭使用而研发的四套工具,不同工具的组合使用可以满足用户的个性化需求。