稀土企业科学运营管理中“双低效应”成因的定量分析

当稀土市场波动,尤其当产品需求与稀土精矿中相应元素的含量不相称时,如果生产计划的综合程度低,时间跨度短,则会出现订单满足率和设备利用率同时低下的恶性状态。这种不良后果称为"双低效应"。建立综合模型,在市场不均衡的情景下定量模拟了双低效应的出现机理。

基于500 kA铝电解槽低效应系数生产管控实践

500kA大型铝电解槽生产工艺管控复杂,多因素诱发阳极效应趋势加剧,对生产过程和碳排放均带来严重影响。文章结合某公司500 kA铝电解生产实践,分析了阳极效应产生的原因,并针对影响因素采取新技术、新工艺和新管理模式的控制措施。实践结果发现,该管控措施能有效降低效应系数、降低物料损耗和PFCs的排放。同时,低效应系数的管控生产丰富了大型预焙铝电解槽的相关实践研究,为绿色铝电冶炼发展提供了新途径具有现实意义。

400kA预焙电解槽低效应系数控制生产实践

本文根据国家"十二五"提出的高耗能企业向节能环保方向发展要求,结合本企业铝电解低效应控制生产,对本企业400kA铝电解槽从投产转入正常生产过程的技术管理,从不同阶段突发阳极效应进行分析,从实践中总结阳极效应控制的生产经验以及取得经济和社会效益,提出铝电解"低效应"管理关键控制点。

免疫低反应状态与移植肾存活

免疫低反应状态是移植受者免疫系统与移植物长期双向作用的结果,其主要特征是对供者抗原呈现特异的低反应。免疫低反应状态与急慢性排斥反应的发生及肾功能均有密切的关系。

铝电解槽降低电耗途径与新技术应用研究

铝电解行业在经历了数年的蓬勃发展壮大后,面临越来越大的资源、能源和环境的压力,已成为影响中国电解铝工业可持续发展的关键因素。节能降耗和发展新技术成为电解铝企业生存与发展的主要课题。该文章总结了铝电解槽降低电耗的主要途径,并介绍了新型结构电解槽新技术应用情况。

Recent progress in CO oxidation over Pt-group-metal catalysts at low temperatures

CO oxidation is probably the most studied reaction in heterogeneous catalysis.This reaction has become a hot topic with the discovery of nanogold catalysts,which are active at low temperatures（at or below room temperature）.Au catalysts are the benchmark for judging the activities of other metals in CO oxidation.Pt-group metals（PGMs） that give comparable performances are of particular interest.In this mini-review,we summarize the advances in various PGM（Pt,Pd,Ir,Rh,Ru）catalysts that have high catalytic activities in low-temperature CO oxidation arising from reducible supports or the presence of OH species.The effects of the size of the metal species and the importance of the interface between the metal and the reducible support are covered and discussed in terms of their promotional role in CO oxidation at low temperatures.

320kA铝电解槽生产的节能探索

节能对于高耗能的铝电解生产来说是企业的重要课题。国内目前平均综合电耗在14500kWh/t-Al左右,由于各个企业之间存在着不同技术思路和管理思路,使得各个企业的电耗不同,好的企业可以达到13700kWh/t-Al左右。中孚实业在320kA铝电解槽生产上经过多年探索,在管理上不断创新,使节能工作一直走在行业前列。

含接地层的薄隐埋层超薄SOI器件特性研究

本文研究了具有薄隐埋层的超薄体SOI器件,讨论了超薄体SOI器件以及减小隐埋层有利于器件短沟道特性的改善。在此基础上通过使用medici软件仿真,进一步得到结论,通过添加接地层(GP),有利于抑制漏致势垒变低效应对器件特性的影响。并借助仿真分析了不同结构的GPSOI器件特性上的区别。

Infrared Spectra and Theoretical Calculations of BS2 and BS2-： Strong Pseudo Jahn-Teller Effect

Laser ablated boron atoms have been reacted with hydrogen sulfide and the reaction products condensed with argon at 4 K, which gave BS2, BS2-, HSBS, and HBS molecules. Reagent isotopic substitution （H2S, H234S, D2S, 10 B, 11B） and variation of boron and hydrogen sulfide concentrations have been used to identify the major products. Both BS2-- and BS2 were identified as linear molecules with no significant difference in the structure parameters, but the B-S anti-symmetric stretching vibration of BS2 is significantly lower than that of BS2-, which is ascribed to pseudo Jahn-Teller effect. Theoretical calculation was employed to have an insight into the interaction nature of the bonds in the corresponding products.

浅谈幼师数学教学现状

幼师学校作为中职院校的一部分,数学在课堂教学中存在着很多弊端,由于各方面的问题,数学教学效果一直不理想.笔者在分析当前中职数学教学现状的基础上,就教学低效应问题,合作学习问题,数学教学生活化问题这三个方面展开以下论述.

Abnormality of Magnetic Behavior and Resistivity of La_(0.7-x)Dy_x Sr_(0.3)MnO_3 (0.00≤x≤0.30)System at Low Temperature

By measuring M-T curves, ρ-T curves and MR-T curves of the samples under different temperatures, the influence of Dy doping （0.00 ≤ x ≤0.30） on the magnetic and electric properties of La0.7-xDyxSr0.3MnO3 has been studied. The experimental results show that, with the increase of the Dy content, the system undergoes a transition from long range ferromagnetic order to the cluster-spin glass state and further to antiferromagnetic order. For the samples with x=0.20 and 0.30, their magnetic behaviors are abnormal at low temperature, and their resistivities at low temperature have a minimum value. These peculiar phenomena not only come from the lattice effect induced by doping, but also from extra magnetic coupling induced by doping.

A speech enhancement algorithm to reduce noise and compensate for partial masking effect

To enhance the speech quality that is degraded by environmental noise,an algorithm was proposed to reduce the noise and reinforce the speech.The minima controlled recursive averaging(MCRA) algorithm was used to estimate the noise spectrum and the partial masking effect which is one of the psychoacoustic properties was introduced to reinforce speech.The performance evaluation was performed by comparing the PESQ(perceptual evaluation of speech quality) and segSNR(segmental signal to noise ratio) by the proposed algorithm with the conventional algorithm.As a result,average PESQ by the proposed algorithm was higher than the average PESQ by the conventional noise reduction algorithm and segSNR was higher as much as 3.2 dB in average than that of the noise reduction algorithm.

Effect of In_(2)O_(3)particle size on CO_(2) hydrogenation to lower olefins over bifunctional catalysts

A reaction-coupling strategy is often employed for CO_(2)hydrogenation to produce fuels and chemicals using oxide/zeolite bifunctional catalysts.Because the oxide components are responsible for CO_(2)activation,understanding the structural effects of these oxides is crucial,however,these effects still remain unclear.In this study,we combined In_(2)O_(3),with varying particle sizes,and SAPO‐34 as bifunctional catalysts for CO_(2)hydrogenation.The CO_(2)conversion and selectivity of the lower olefins increased as the average In_(2)O_(3)crystallite size decreased from 29 to 19 nm;this trend mainly due to the increasing number of oxygen vacancies responsible for CO_(2) and H_(2) activation.However,In_(2)O_(3)particles smaller than 19 nm are more prone to sintering than those with other sizes.The results suggest that 19 nm is the optimal size of In_(2)O_(3)for CO_(2)hydrogenation to lower olefins and that the oxide particle size is crucial for designing catalysts with high activity,high selectivity,and high stability.

Stark Effect Dependence on Hydrogenic Impurities in GaAs Parabolic Quantum-Well Wires

The ground-state and lowest excited-state binding energies of a hydrogenic impurity in GaAs parabolic quantum-well wires （Q WWs） subjected to external electric and magnetic fields are investigated using the finite-difference method within the quasi-one-dimensional effective potential model. We define an effective radius Pen of a cylindrical QWW, which can describe the strength of the lateral confinement. For the ground state, the position of the largest probability density of electron in x-y plane is located at a point, while for the lowest excited state, is located on a circularity whose radius is Pen. The point and circularity are pushed along the left haft of the center axis of the quantum-well wire by the electric field dire ted along the right half. When an impurity is located at the point or within the circularity, the ground-state or lowest excited-state binding energies are the largest; when the impurity is apart from the point or circularity, the ground-state or lowest excited-state binding energies start to decrease.

Enhanced treatment of water with low turbidity:Combined effects of permanganate, PAM and recycled sludge

The effectiveness of enhancing treatment of water with low turbidity through combined effects of permanganate oxidation, PAM aiding coagulation and sludge recycling was investigated through continuous bench scale studies. In comparing with ferric chloride coagulation, only recycling sedimentation sludge was ineffective in enhancing treatment of water with low turbidity. PAM with recycled sludge showed positive effects, and the additional permanganate dosing exhibited the best potential of favoring coagulation, which leaded to much lower effluent turbidity and CODMa. Additionally, it was observed that the optimal permanganate dosage was 0. 4 mg/ L and the higher permanganate dosage exhibited inhibiting effects for pollutants removal. SEM analysis indicated that the floes were loosely formed and the particle diameter was critically low for ferric chloride coagulation process. Comparatively, the addition of PAM and permanganate with recycled sludge facilitated the aggregation of tinny particles onto compact PAM polymer chains, therefore contributing to the formation of compact floes with high particle diameter. The combined employment of recycled sludge, PAM and permanganate showed the best potential of favoring coagulation, mainly through synergistic effects between seeding, polymer bridging and increasing effective collision in mechanism. Additionally, the variation of Fe and Mn concentration after recycling and sedimentating units was studied for the processes, and the main species was also investigated for elements Fe and Mn. Sludge recycling and permanganate addition did not increase Fe and Mn concentration in the sedimented water.

Differential Cross Sections of F+HD→DF+H Reaction at Collision Energies from 3.03 meV to 17.97 meV

The prototypical reaction of F+HD→DF+H was investigated at collision energies from 3.03 meV to 17.97 meV using a crossed molecular beam apparatus with multichannel Rydberg tagging time-of-flight detection.Significant contributions from both the BornOppenheimer(BO)forbidden reaction F^(*)(^(2)P_(1/2))+HD→DF+H and the BO-allowed reaction F(^(2)P_(3/2))+HD→DF+H were observed.In the backward scattering direction,the contribution from the BO-forbidden reaction F^(*)(^(2)P_(1/2))+HD was found to be considerably greater than the BO-allowed reaction F(^(2)P_(3/2))+HD,indicating the non-adiabatic effects play an important role in the dynamics of the title reaction at low collision energies.Collision-energy dependence of differential cross sections(DCSs)in the backward scattering direction was found to be monotonously decreased as the collision energy decreases,which does not support the existence of resonance states in this energy range.DCSs of both BO-allowed and BO-forbidden reactions were measured at seven collision energies from 3.03 meV to 17.97 meV.It is quite unexpected that the angular distribution gradually shifts from backward to sideway as the collision energy decreases from 17.97 meV to 3.03 meV,suggesting some unknown mechanisms may exist at low collision energies.

Strength weakening effect of high static pre-stressed granite subjected to low-frequency dynamic disturbance under uniaxial compression

This study aimed to elucidate the strength weakening effect of high static pre-stressed rocks subjected to low-frequency disturbances under uniaxial compression.Based on the uniaxial compressive strength(UCS)of granite under static loading,70%,80%,and 90%of UCS were selected as the initial high static pre-stress(σ_(p)),and then the pre-stressed rock specimens were disturbed by sinusoidal stress with amplitudes of 30%,20%,and 10%of UCS under low-frequency frequencies(f)of 1,2,5,and 10 Hz,respectively.The results show that the rockburst failure of pre-stressed granite is caused by low-frequency disturbance,and the failure strength is much lower than UCS.When theσp or f is constant,the specimen strength gradually decreases as the f or σ_(p) increases.The experimental study illustrates the influence mechanism of the strength weakening effect of high static pre-stress rocks under low-frequency dynamic disturbance,that is,high static pre-stress is the premise and leading factor of rock strength weakening,while low-frequency dynamic disturbance induces rock failure and affects the strength weakening degree.

Solvent Effects on Spectral Property and Dipole Moment of the Lowest Excited State of Coumarin 343 Dye

Steady-state absorption and fluorescence spectra, and time-resolved fluorescence spectra of coumarin 343 （C343） were measured in different solvents. The effect of the solvent on the spectral properties and dipole moment of the lowest excited state of C343 were investigated. It was found that the absorption and fluorescence spectra red-shifted slightly and strongly with increasing solvent polarity, respectively, because the charge distribution of the excited state leaded to the increasing difference between the absorption and fluorescence spectra with increasing solvent polarity. The dipole moment of the lowest excited state of C343 was determined from solvatochromic measurements and the quantum chemical calculation, and the results obtained from these two methods were fully consistent. Investigations of the time-resolved fluorescence of C343 in different solvents indicated that the fluorescence lifetimes increased nearly linearly with 4.45 ns in water. This can be ascribed between C343 and hydrogen donating increasing solvent polarity from 3.09 ns in toluene to to the intermolecular hydrogen bonding interactions solvents

Roll Vortices in the Boundary Layer Caused by a Concave Wind Profile: A Theoretical Study

The present study solves a two-layer atmospheric wave equation model with a lower atmosphere concave wind profile and cold-air outbreak over sea, while simultaneously proving that such a wind shear may cause neutral boundary layer roll vortices in the presence of disturbing sources upstream. Without thermal effects, the wind shear-induced waves have band structures at the top of the boundary layer that are similar to cloud street patterns observed over sea. This study proves that dynamic and thermal effects can act independently to initiate the roll vortices in the lower atmosphere. At the same time, a quantitative comparison shows that dynamic effects play a large role in the formation of roll vortices in the initial stage of cold-air outbreak and will be surpassed by thermal effects soon after surface heating commences.