CO_(2) mineralization by typical industrial solid wastes for preparing ultrafine CaCO_(3): A review

Mineral carbonation is a promising CO_(2) sequestration strategy that can utilize industrial wastes to convert CO_(2) into high-value CaCO_(3).This review summarizes the advancements in CO_(2) mineralization using typical industrial wastes to prepare ultrafine CaCO_(3).This work surveys the mechanisms of CO_(2) mineralization using these wastes and its capacities to synthesize CaCO_(3),evaluates the effects of carbonation pathways and operating parameters on the preparation of CaCO_(3),analyzes the current industrial application status and economics of this technology.Due to the large amount of impurities in solid wastes,the purity of CaCO_(3) prepared by indirect methods is greater than that prepared by direct methods.Crystalline CaCO_(3) includes three polymorphs.The polymorph of CaCO_(3) synthesized by carbonation process is determined the combined effects of various factors.These parameters essentially impact the nucleation and growth of CaCO_(3) by altering the CO_(2) supersaturation in the reaction system and the surface energy of CaCO_(3) grains.Increasing the initial pH of the solution and the CO_(2)flow rate favors the formation of vaterite,but calcite is formed under excessively high pH.Vaterite formation is favored at lower temperatures and residence time.With increased temperature and prolonged residence time,it passes through aragonite metastable phase and eventually transforms into calcite.Moreover,polymorph modifiers can decrease the surface energy of CaCO_(3) grains,facilitating the synthesis of vaterite.However,the large-scale application of this technology still faces many problems,including high costs,high energy consumption,low calcium leaching rate,low carbonation efficiency,and low product yield.Therefore,it is necessary to investigate ways to accelerate carbonation,optimize operating parameters,develop cost-effective agents,and understand the kinetics of CaCO_(3) nucleation and crystallization to obtain products with specific crystal forms.Furthermore,more studies on life cycle assessment(LCA)should be conducted to fully confirm the feasibility of the developed technologies.

复杂性阑尾炎的影响因素及与术前延误的关系

目的探讨复杂性阑尾炎易发因素及其与术前延误的关系,以期为提高急性阑尾炎的治疗效果提供理论依据。方法选取2016年11月-2017年12月绵阳市第三人民医院确诊为急性阑尾炎的患者562例。按最终诊断分为复杂性阑尾炎和非复杂性阑尾炎两组,比较组间人口学、症状体征、辅助检查及术前延误时间等临床特点的差异。结果 Logistic回归多因素分析显示年龄≥60岁、合并慢性病、粪石嵌顿、阑尾长度>10 cm、总体延误(≤24 h,>24~48 h,>48~72 h,>72 h)是复杂性阑尾炎的独立危险因素。结论术前总体延误会影响急性阑尾炎的病情和预后,对急性阑尾炎患者,应及早进行手术。

A novel approach for fabricating a CNT/AlSi composite with the self-aligned nacre-like architecture by cold spraying

A fully dense carbon nanotubes (CNTs) reinforced AlSi matrix composite with the multiscale nacre-like architecture was designed and successfully realized by flake powder metallurgy followed by cold spraying (CS). The nanolaminated and ultrafine-grained structure initially created in the CNT/AlSi flaky powder was perfectly conserved, due to the typical ‘cold’ feature of CS. As discussed based on finite element analysis and single splat observation, self-alignment behavior of the flaky powders during impact also allowed the formation of the microlaminated structure. Hence, the scalable CS technique opens a new avenue for bioinspired material design and fabrication with complex shape.

Microchannel reactors for Fischer-Tropsch synthesis:Experimental investigation and mathematical modeling

The Fischer-Tropsch synthesis is a significant technology for converting coal,natural gas,and biomass into synthetic fuels.In recent years,the use of microchannel reactors for the Fischer-Tropsch synthesis has attracted significant attention.Fischer-Tropsch synthesis experiments were carried out in a microchannel reactor and the influences of reaction conditions on the experimental results were investigated in this study.Based on the experimental data,a dynamic multi-component pseudo-homogeneous variable-volume flow model of microchannel reactors for the Fischer-Tropsch synthesis was built to determine the pressure-,velocity-,conversion-and(component-wise)concentration-distributions in reaction channels.The model takes into account the combined effects of gas volume expansion caused by the frictional pressure drop and gas volume contraction caused by reaction consumption.A novel effective method for calculating the pressure and superficial gas velocity values in microchannel reactors was proposed in the model.Besides that,two sets of experimental data were selected from references to evaluate the validity and accuracy of the model.The reaction performances in the microchannels were analyzed carefully based on the calculated results.

Investigation of transport properties of perovskite single crystals by pulsed and DC bias transient current technique

Time-of-flight(ToF)transient current method is an important technique to study the transport characteristics of semiconductors.Here,both the direct current(DC)and pulsed bias ToF transient current method are employed to investigate the transport properties and electric field distribution inside the MAPbI_(3) single crystal detector.Owing to the almost homogeneous electric field built inside the detector during pulsed bias ToF measurement,the free hole mobility can be directly calculated to be about 22 cm^(2)·V^(-1)·s^(-1),and the hole lifetime is around 6.5μs–17.5μs.Hence,the mobility-lifetime product can be derived to be 1.4×10^(-4)cm^(2)·V^(-1)–3.9×10^(-4)cm^(2)·V^(-1).The transit time measured under the DC bias deviates with increasing voltage compared with that under the pulsed bias,which arises mainly from the inhomogeneous electric field distribution inside the perovskite.The positive space charge density can then be deduced to increase from 3.1×10^(10)cm^(-3)to 6.89×10^(10)cm^(-3)in a bias range of 50 V–150 V.The ToF measurement can provide us with a facile way to accurately measure the transport properties of the perovskite single crystals,and is also helpful in obtaining a rough picture of the internal electric field distribution.

Some New Delay Integral Inequalities Based on Modified Riemann-Liouville Fractional Derivative and Their Applications

By using the properties of modified Riemann-Liouville fractional derivative, some new delay integral inequalities have been studied. First, we offered explicit bounds for the unknown functions, then we applied the results to the research concerning the boundness, uniqueness and continuous dependence on the initial for solutions to certain fractional differential equations.

Lyapunov-Type Inequalities for Conformable BVP

In this paper, we present Lyapunov-type inequality for conformable BVP with the conformable fractional derivative of order 1≤2 and 2≤3 with corresponding boundary conditions. We obtain the Lyapunov-type inequality by a construction Green’s function and get its corresponding maximum value. Application to the corresponding eigenvalue problem is also discussed.

Evaluation of Students'Performance in Specialized Courses in Yanbian Agriculture College by Variance

The performance of college students'professional courses is an index to evaluate their academic status,so the performance of professional courses has a certain significance.In the process of assigning homework to teachers and taking exams in universities,the performance of specialized courses is regarded as the standard for students to study well.Because students'understanding and follow-up are often assessed on the basis of their usual seriousness and attendance in class,homework and exams,it is necessary to analyze their final grades to assess their actual situation.Test scores were evaluated using variances and covariances.This paper discusses how to evaluate the final achievement from the distribution of achievement.

Convergence Proving of the Theoretical&True Elongation Inequalities by Derivation and Analogy

According to LN?,theoretical&true elongation of tensile,and by adopting the increasing function of formulas with the derivation and analogy methods,the elongation formula of 0<(1+ε)^1/ε<e&0<ε^1/ε<1&four convergences are deduced too whenε>1 and 0<ε<1.The inequalities of LNε<εand LN(1+ε)<εand LN(1+ε)>LNεare deduced ifε>1 and 0<ε<1 in material dynamics.Finally the conclusions of LNε<εand LNε<LN(1+ε)<εare deduced together ifε>1 and 0<ε<1.

Modeling of Economic Cost Distribution in Screw Thread

The screw threading produce is a important process course.The economics modeling is established in this paper so this process will be investigated.In this paper modeling of process is analyzed.The Q and cost decreases with the increasing quantity while the same turn as AC>AFC>MC is found.AC and AFC is main factors to affect quantity then MC do.It fits to concept of them well.The cost AC and AFC is higher upon L=4 than L=6 while MC is higher upon L=6 than L=4.Meantime the TC and VC is higher upon L=6 than that upon L=4,is the near parallel line.The TC>VC is turn to affect cost.There is a difference for them.TC and VC is main effective costs to compare with AC,AFC&MC.The TC and VC become bigger upon K=5 than K=7.

Technological Analysis on Motor Stall and Its Perspective

The brush lock is due to assembly tightly during assembling three gripper so that it curls after some time in motor and bare motors.The motor happen to have current decreasing and cause rotary too slowly is an important technique problem.At last the motor hasn’t worked due to disconnection.It give company to bring assembly issue for customers.So the motor stall is main issue in motor working.We shall pay more attention to it necessarily and shall be strict quality inspection and we shall monitor the flow line for the sake of decreasing it.We shall solve the problem as soon as possible and communicate with the customer engineers.Unloaded rotation is radical in the base inspection.The engineer need to negotiate with supplying engineers for the qualified material of brush.Increasing inspection into more times is a method to decrease unqualified brushes.Some experiment method is explained to analyze for customer engineers.Two kinds of motors ie.stepping and asynchronous motor and motors used in future in car is explained to further knowledge to motor’s application.Such as the experiment with torque,voice and electric voltage converter.The pseudo soldering results the slow rotary.The reverse voltage is a reason for a motor to slow rotary even stall.

The Simulation on Dynamic of Rotary Inertia and Engine’s Inflamer in Light Vehicle

According to formula we can simulate their driven force and acceleration.The mechanical formula is used to obtain dynamics is used to simulate.The driven force increases when torque increases and tire diameter decreases.We need torque to increase so this is our plan.Acceleration raises when torque raises and it reduces when its weight raises.With the decreasing of radius of road the centripetal acceleration is increasing in the condition of light vehicle.It is that it decreases sluggishly before 0.35m/s2 then it maintains a steep decline to 0.62m/s2 and at last becomes sluggish again.It is valued that the economical efficiency about consumed fuel under different power.In the time of 0.2hr the fuel inflamer inclines sharply first then turns stable.It is the smallest value.Beyond it the fuel maintains a high value all the time.The discharged pollution gas decreases with the decreasing initial temperature.The low initial temperature is good to fuel gas.Meantime the smallest incline range is 300~350K which explains that it is the most save one.

The Dynamic Simulation of Rotary Inertia on Light vehicle-Slope I

According to formula we can simulate their driven force and acceleration on the slope.The mechanical formula is used to obtain force and theoretical dynamics in the slope.The driven force decreases when rotation increases.When power increases the acceleration increases.it reduces when its weight raises.It is found that the a will decrease as slope becomes high from 5 to 11°to 22°,which fit the formula too.Meantime as the radius is high from 0.3m to 0.4m to 0.47m a will be low.The needed force will increase as the slope decline becomes big at the same power.

Dynamics Models of Crank in Motor Housing Process

With regards to the assembly line of cost control of Dechang(HK)company,the motor housing’s cost control of process will be necessarily respected.Because the supply quantity is big in a machine the price of motor housing is small,so that the cost control of automatic production line is significant with modeling.It is found that the control of equipment includes in shaft and crank linkage for benefit which also needs to be controlled in detail.For the sake of benefits can we fundamentally resolve the main problem of high cost process.

The Study on Simulation of Resistance in Stall Motor

The stall phenomenon which happens in loaded motor is unqualification in application.Meanwhile it may measure the maximum property of motor in manufacture.So the phenomenon is analyzed to find a simulation of electrical state to predict the maximum currency and torque which is a necessary method to be proceeded up to now before design.We find that the simulation fits well to the reference.The conditions of t=6s,U=12V result in the biggest stall force according to rotation to change time and voltage.Then it is t=8s,U=10V;t=10s,U=8V and t=12s,U=6V in turns.As for torque it is t=6s,U=12V;t=8s,U=10V;t=6s,U=12V and t=12s,U=6V in truns.

关于收缩率和延伸率间偏差和颈缩分析I

根据收缩率和延伸率间密度不变时的公式可以推倒出它们之间颈缩的不等式。曲线很好地说明了它的走势。由偏差关系得出在小于14%时收缩偏差较好,在中间一段延伸偏差较好,大于一定值收缩率偏差又变好的规律。在64%偏差率时收缩率的值小于延伸率,它的真实性高1.32倍以上,最大偏差为1.64。推导出(√S0)3-S√S0+S0-2S<0等两个公式为颈缩发生推倒公式。据文献统计收缩率值在大于25%时比较多,而延伸率则在30%以下较多。双晶由剪应力引起,转位由拉应力引起。

A New Study on the Superplasticity of TiAl Alloys

The superplasticity of Ti-46.7Al-2.2Cr(at.%)alloy was studied by mathematical induction.It is found that Zener Hollomon relative formula and there are serious deflections.According to the true superplastic stress and true strain curves,the deflection values of n=-7.46 and B=1439MPa are obtained,indicating that the limit of n>0 has been exceeded,which needs to be characterized by a negative sign.This shows that it conforms to the principle that the smaller n is,the better superplasticity is,but the problem that it has become a negative number needs to attract the attention of peers meantime B is a better match.

The Relationship between Quality and Efficiency in Business Management

Quality and efficiency are the two most important factors for the survival of an enterprise.Quality is essential,then efficiency.Only the quality in the first place,to ensure the efficiency of the implementation.You can imagine when the first step didn’t happen.So in the enterprise management should always put the quality in mind,always inspire the concept of quality.Don’t put efficiency in your mouth every day,because it is too snobbish and haste makes waste.So recruit some of the level of people to serve for the enterprise,and reuse it,in order to constantly achieve new things,so that the quality gradually up.And continuous contact with workers,to understand the real content of the product and equipment,so that the increasingof the product quality.In addition,the requirements of customers should be discussed quickly and communicated with the production department,so that the product quality can be improved and the cost can be reduced to seek higher prices.The purchase order decides technology which decides quality and efficiency as well.The latter determines goods quality and quantity through equipment by staffs who is capable of the equipment such as machinery design.Another is mould which could be designed too through fit size and material.

A Retrospective Study of Product Quality

Quality is a product to the customer after the test and use of the performance of the product in the index.If there is no problem,it is considered to be a product with good performance;if there is a problem,it becomes a product with poor performance.When a certain number of products have no quality problem after the experiment and operation,it is a good product.However,the evaluation of the use of the assembly after a certain period of time after the final customer should also be discussed.Only in this way can the product quality be improved fundamentally.A/S is a significant process when the retrospective production is done for its quality to be investigated.Retrospection becomes a new way to study and innovate manufacturer quality currently in busyness.In modern society the retrospect as A/S is more and more prevail at shopping mall in big city for customer convenient application.In terms of their rapid and good mending the excellent brand will be established for product quality yearby-year.

Development of Flake Powder Metallurgy in Fabricating Metal Matrix Composites:A Review

Powder metallurgy （PM） is one of the most applied processes in the fabrication of metal matrix composites （MMCs）. Recently, a novel PM strategy called flake PM was developed to fabricate MMCs with nano-laminated or hierarchical architectures. The name ＂flake PM＂ was derived from the use of flake metal powders, which could benefit the uniform dispersion of reinforcements in the metal matrices and thus result in balanced strength and ductility. Flake PM has been proved to be successful in the dispersion of nano aluminum oxides, carbon nanotubes, graphene nano-sheets, and microsized B4C particles in aluminum or copper matrix. This paper reviews the technique and mechanism developments of flake PM in previous studies, and foresees the future develop of this new fabricating method.