Temperature-dependent photoluminescence on organic inorganic metal halide perovskite CH_3NH_3Pb I_(3-)Cl_ prepared on ZnO/FTO substrates using a two-step method

Temperature-dependent photoluminescence characteristics of organic-inorganic halide perovskite CH3NH3Pb I3-xClx films prepared using a two-step method on ZnO/FTO substrates were investigated. Surface morphology and absorption characteristics of the films were also studied. Scanning electron microscopy revealed large crystals and substrate coverage. The orthorhombic-to-tetragonal phase transition temperature was-140 K. The films＇ exciton binding energy was 77.6 ± 10.9 meV and the energy of optical phonons was 38.8 ± 2.5 meV. These results suggest that perovskite CH3NH3Pb I（3-x）Clx films have excellent optoelectronic characteristics which further suggests their potential usage in perovskitebased optoelectronic devices.

Applying the Dynamic Two-Step Method to Forecast Remaining Oil Distribution of Lower Series ,Xiaermen Oilfield

The distribution of remaining oil is often described qualitatively. The remaining oil distributed in the whole reservoir is calculated according to the characteristics of the space distribution of the saturation of remaining oil. Logging data are required to accomplish this. However, many such projects cannot be completed. Since the old study of remaining oil distribution could not be quantified efficiently, the ＂dynamic two-step method＂ is presented. Firstly, the water cut of every flow unit in one well at one time is calculated according to the comprehensive water cut of a single well at one time. Secondly, the remaining oil saturation of the flow unit of the well at one time is calculated based on the water cut of the flow unit at a given time. The results show that ＂dynamic two-step method＂ has characteristics of simplicity and convenience, and is especially suitable for the study of remaining oil distribution at high water-cut stage. The distribution of remaining oil presented banding and potato form, remaining oil was relatively concentrated in faultage neighborhood and imperfect well netting position, and the net thickness of the place was great. This proposal can provide an effective way to forecast remaining oil distribution and enhance oil recovery, especially applied at the high water-cut stage.

The convergence ball and error analysis of the two-step Secant method

Under the assumption that the nonlinear operator has Lipschitz continuous divided differences for the first order,we obtain an estimate of the radius of the convergence ball for the two-step secant method.Moreover,we also provide an error estimate that matches the convergence order of the two-step secant method.At last,we give an application of the proposed theorem.

A new two-step variational model for multiplicative noise removal with applications to texture images

Multiplicative noise removal problems have attracted much attention in recent years.Unlike additive noise,multiplicative noise destroys almost all information of the original image,especially for texture images.Motivated by the TV-Stokes model,we propose a new two-step variational model to denoise the texture images corrupted by multiplicative noise with a good geometry explanation in this paper.In the first step,we convert the multiplicative denoising problem into an additive one by the logarithm transform and propagate the isophote directions in the tangential field smoothing.Once the isophote directions are constructed,an image is restored to fit the constructed directions in the second step.The existence and uniqueness of the solution to the variational problems are proved.In these two steps,we use the gradient descent method and construct finite difference schemes to solve the problems.Especially,the augmented Lagrangian method and the fast Fourier transform are adopted to accelerate the calculation.Experimental results show that the proposed model can remove the multiplicative noise efficiently and protect the texture well.

Solution of Nonlinear Integro Differential Equations by Two-Step Adomian Decomposition Method (TSAM)

The Adomian decomposition method (ADM) can be used to solve a wide range of problems and usually gets the solution in a series form. In this paper, we propose two-step Adomian Decomposition Method (TSAM) for nonlinear integro-differential equations that will facilitate the calculations. In this modification, compared to the standard Adomian decomposition method, the size of calculations was reduced. This modification also avoids computing Adomian polynomials. Numerical results are given to show the efficiency and performance of this method.

Arrhenius relationship and two-step scheme in AF hyperdynamics simulation of diffusion of Mg/Zn interface

The accelerating factor （AF） method is a simple and appropriate way to investigate the atomic long-time deep diffusion at solid-solid interface. In the framework of AF hyperdynamics （HD） simulation, the relationship between the diffusion coefficient along the direction of z-axis which is normal to the Mg/Zn interface and temperature was investigated, and the AF＇s impact on the diffusion constant （D0） and activation energy （Q^＊） was studied. Then, two steps were taken to simulate the atomic diffusion process and the formation of new phases： one for acceleration and the other for equilibration. The results show that： the Arrhenius equation works well for the description of Dz with different accelerating factors; the AF has no effect on the diffusion constant Do in the case of no phase transition; and the relationship between Q＊ and Q conforms to Q^＊=Q/A. Then, the new Arrhenius equation for AFHD is successfully constructed as Dz=Doexp[-Q/（ART）]. Meanwhile, the authentic equilibrium conformations at any dynamic moment can only be reproduced by the equilibration simulation of the HD-simulated configurations. Key words： accelerating factor method; Arrhenius equation; two-steps scheme; Mg/Zn interface; hyperdynamic simulation

要素投入对中国工业碳生产率的影响研究——来自Heckman两阶段的经验数据

在清洁低碳、安全高效的能源体系建设过程中,中国工业行业作为碳排放和能源消费重要主体,需积极提升碳生产效率,为能源体系建设做出贡献。基于理论分析及Heckman两阶段模型,选取2019年中国工业41个细分行业的数据,构建了工业碳生产率影响实证模型,研究劳动力投入、资本、技术创新、能源消费结构对工业碳生产率的影响方式及程度。经实证,劳动力投入和技术创新显著促进工业碳生产率提升,资本对工业碳生产率无促进作用,能源消费结构对工业碳生产率的影响程度尚不明确。针对以上结论,提出通过培训等方式促进劳动力素质提升,避免劳动粗放投入造成资源错配;推动冗余资本流向人才培养、技术研发;积极开展技术创新等建议。

牧户参与草原生态旅游经营意愿及影响因素研究——基于Heckman两阶段模型的分析

本研究基于内蒙古额尔古纳市9个村落及生产队500份调研数据,通过构建Heckman两阶段模型识别影响牧户参与草原生态旅游经营的意愿及预期收益影响因素。结果表明:牧户是否愿意参与草原生态旅游经营和预期收益水平是两个不同阶段的选择,主要受户主受教育程度、经济效益认知、传统经营习惯的影响;牧户是否愿意参与经营受户主受教育程度、经济效益认知、环境效益认知、与邻里亲朋经营经验的交流程度、亲朋好友是否参与草原生态旅游经营、政府激励政策的显著正向影响,受户主年龄、传统经营习惯遵循程度的显著负向影响;牧户参与经营的预期收益水平受户主受教育程度、牧户拥有牲畜数量、人均草场面积、经济效益认知、社会效益认知、传统经营习惯遵循程度、是否参与合作组织的正向显著影响。本研究提出了提升牧户参与草原生态旅游的经营意愿、促进草原生态旅游可持续发展的政策建议。

A Novel Method of Fabricating a Well-Faceted Large-Crystal Diamond Through MPCVD

A novel method was developed to deposit a large crystal diamond with good facets up to 1000 μm on a tungsten substrate using a microwave plasma enhanced chemical vapor deposition （MPCVD）. This method consists of two steps, namely single-crystal nucleation and growth. Prior to the fabrication of the well-faceted, large crystal diamond, an investigation was made into the nucleation and growth of the diamond which were affected by the O2 concentration and substrate temperature. Deposited diamond crystals were characterized by scanning electron microscopy and micro-Raman spectroscopy. The results showed that the conditions of single-crystal nucleation were appropriate when the ratio of H2/CH4/O2 was about 200/7.0/2.0, while the sub- strate temperature Ts of 1000℃ to 1050℃ was the appropriate range for single-crystal diamond growth. Under the optimum parameters, a well-faeeted large crystal diamond was obtained.

The Research on Biogas Power Generation by Two Step Method

The paper aims to demonstrate the system of SANYI biogas power generation by two-step method which can produce methane and generate electricity effectively and stably.So it can be stable synchronization meshwork energy source establishment and provide references to develop an effective and stable project of producing methane and generating electricity.

In-depth understanding of ionic liquid assisted perovskite film formation mechanism for two-step perovskite photovoltaics

Ionic liquids(ILs)have been widely applied in the one-step fabrication of perovskite with noticeable enhancement in the device performance.However,in-depth mechanism of ionic-liquid-assisted perovskite film formation is not well understood for also important two-step perovskite fabrication method,with better control of crystallization behavior.In this work,we introduced ionic liquid methylammonium formate(MAFa)into organic salt to produce perovskite film via a two-step method.Systematic investigations on the influence of MAFa on the perovskite thin film formation mechanism were performed.Ionic liquid is shown to assist lowering the perovskite formation enthalpy upon the density functional theory(DFT)calculation,leading to an accelerated crystallization process evidenced by in-situ UV-Vis absorption measurement.A gradient up-down distribution of ionic liquid has been confirmed by timeof-flight SIMS.Importantly,besides the surface passivation,we found the HCOO-can diffuse into the perovskite crystals to fill up the halide vacancies,resulting in significant reduction of trap states.Uniform perovskite films with significantly larger grains and less defect density were prepared with the help of MAFa IL,and the corresponding device efficiency over 23%was obtained by two-step process with remarkably improved stability.This research work provides an efficient strategy to tune the morphology and opto-electronic properties of perovskite materials via ionic-liquid-assisted two-step fabrication method,which is beneficial for upscaling and application of perovskite photovoltaics.

A class of twostep continuity Runge-Kutta methods for solving singular delay differential equations and its convergence

An idea of relaxing the effect of delay when computing the Runge-Kutta stages in the current step and a class of two-step continuity Runge-Kutta methods （TSCRK） is presented. Their construction, their order conditions and their convergence are studied. The two-step continuity Runge-Kutta methods possess good numerical stability properties and higher stage-order, and keep the explicit process of computing the Runge-Kutta stages. The numerical experiments show that the TSCRK methods are efficient.

A Remarkable Chord Iterative Method for Roots of Uncertain Multiplicity

In this note we at first briefly review iterative methods for effectively approaching a root of an unknown multiplicity. We describe a first order, then a second order estimate for the multiplicity index m of the approached root. Next we present a second order, two-step method for iteratively nearing a root of an unknown multiplicity. Subsequently, we introduce a novel chord, or a two- step method, not requiring beforehand knowledge of the multiplicity index m of the sought root, nor requiring higher order derivatives of the equilibrium function, which is quadratically convergent for any , and then reverts to superlinear.

Explicit solutions to some nonlinear physical models by a two-step ansatz

Explicit solutions are derived for some nonlinear physical model equations by using a delicate way of two-step ansatz method.

General Convergence Analysis for Three-step Projection Methods and Applications to Variational Problems

First a general model for a three-step projection method is introduced, and second it has been applied to the approximation solvability of a system of nonlinear variational inequality problems in a Hilbert space setting. Let H be a real Hilbert space and K be a nonempty closed convex subset of H. For arbitrarily chosen initial points x0, y0, z0 ∈ K, compute sequences xn, yn, zn such thatT ： K→ H is a nonlinear mapping onto K. At last three-step models are applied to some variational inequality problems.

A Two-Step Modulus-Based Matrix Splitting Iteration Method Without Auxiliary Variables for Solving Vertical Linear Complementarity Problems

In this paper,a two-step iteration method is established which can be viewed as a generalization of the existing modulus-based methods for vertical linear complementarity problems given by He and Vong(Appl.Math.Lett.134:108344,2022).The convergence analysis of the proposed method is established,which can improve the existing results.Numerical examples show that the proposed method is efficient with the two-step technique.

政府补贴、所有权性质与企业研发决策

本文将企业研发行为分为"是否研发"和"投入多少"两个阶段,就政府补贴对不同所有制企业研发决策的影响进行研究.理论方面,构建企业研发决策的两阶段模型,讨论了补贴对企业研发投资的作用机制.实证方面,以中国工业企业为对象,选择Heckman两步法和2SLS分别处理了样本选择性偏误及变量间的内生性问题,对来自国有、私营和外资企业的分类样本进行了检验,结果表明:在不同的所有权性质下,政府补贴对企业研发投资的作用存在一定差别,国有企业面对优惠政策的倾斜和需要担负的社会责任,从事技术创新活动的概率较高,但由于特殊的产权关系和预算软约束等原因,缺乏扩大研发投入的动力;对于治理机制完善的外资企业和处于市场竞争弱势地位的私营企业而言,政府补贴的研发激励效果更为明显.

社会资本能持续缓解农户信贷约束吗

本文采用Heckman两步法从微观层面分析了当前农户所拥有的不同的社会资本是否能够缓解信贷约束,提高信贷可得性的问题。研究结果表明,农户社会资本中以血缘为基础的强关系减少,而以朋友为主的弱关系增加,虽然能在一定程度上缓解农户的信贷约束,但这种以弱关系为主的社会资本是需要农户投入资金进行维持的,并不完全是穷人的社会资本。此外,家庭收入主要来源于工商经营的农户以及人情支出越多的农户更可能发生融资行为;户主是男性以及社会地位和收入水平越高的农户受到的信贷约束越小。

“是否研发”与“投入多少”:兼论企业研发投资的两阶段决策

研发投资是企业提高技术创新能力和市场竞争力的重要途径。与以往研究不同,针对中国企业研发参与度小和投入强度低的现实,本文从企业属性、行业特征和外部冲击三个角度探究了研发投资的决定因素及作用机制,进而利用Heckman两步法建立选择和投资方程,以2007年中国工业企业的微观数据和工业行业的中观数据为样本,就企业研发决策的两面性问题进行了实证检验,发现企业研发行为的选择性偏误确实存在,是否研发与投入多少会受到不同因素的制约,来自所有制分组的回归结果显示,企业性质是影响研发投资的重要因素,国有、外资和私营企业在研发决策机制方面存在巨大差异。

资源禀赋与企业能力会影响企业质量认证吗?——来自225家农业龙头企业的证据

基于对225家农业龙头企业的调查数据,利用Heckman(赫克曼)两步法,从资源能力观的视角研究资源禀赋和企业能力对农业企业是否实施质量认证以及多重认证频度决策的影响。研究表明:(1)规模、技术、品牌、股权集中度、盈利能力和偿债能力等内在特征是影响企业是否实施质量认证的显著因素;(2)规模越大、技术水平和决策者素质越高、盈利能力、偿债能力和营运能力越强的企业越倾向于实施多重质量认证;(3)经营模式和经营战略对企业多重质量认证行为有显著影响,且不同经营模式的边际影响存在显著差异。总之,资源禀赋和企业能力的异质性较好地解释了在面临同样的外部环境时,不同企业之间质量认证行为的差异。