Enhancing Software Effort Estimation:A Hybrid Model Combining LSTM and Random Forest

Effort estimation plays a crucial role in software development projects,aiding in resource allocation,project planning,and risk management.Traditional estimation techniques often struggle to provide accurate estimates due to the complex nature of software projects.In recent years,machine learning approaches have shown promise in improving the accuracy of effort estimation models.This study proposes a hybrid model that combines Long Short-Term Memory(LSTM)and Random Forest(RF)algorithms to enhance software effort estimation.The proposed hybrid model takes advantage of the strengths of both LSTM and RF algorithms.To evaluate the performance of the hybrid model,an extensive set of software development projects is used as the experimental dataset.The experimental results demonstrate that the proposed hybrid model outperforms traditional estimation techniques in terms of accuracy and reliability.The integration of LSTM and RF enables the model to efficiently capture temporal dependencies and non-linear interactions in the software development data.The hybrid model enhances estimation accuracy,enabling project managers and stakeholders to make more precise predictions of effort needed for upcoming software projects.

The Influence of Academic Self-Efficacy on Learning Engagement in Online Education in China:The Mediating Role of Effort

The shift towards online intelligent learning has become the norm in education and is now a fundamental part of modern educational activities.However,this new model can influence students’learning behavior and lead to changes in their approach to learning.Based on online intelligent learning,we investigated how the academic self-efficacy of nursing students affects their engagement with learning and explored the role of academic attribution as a mediator.Five hundred fifty-three nursing college students from Hebei and Hunan provinces in China participated in the online questionnaire.The results revealed that effort plays a mediating role in the relationship between academic self-efficacy and learning engagement.

Material embrittlement in high strain-rate loading

Material embrittlement is often encountered in machining,heat treatment,hydrogen and lowtemperature conditions among which machining is strain-rate related.More strain-rate evoked embrittlement is expected in material loading processes,such as in high-speed machining and projectile penetration.In order to understand the fundamental mechanisms of the strain-rate evoked material embrittlement,this study is concerned with the material responses to loading at high strain-rates.It then explores the strain-rate evoked material embrittlement and fragmentation during high strain-rate loading processes and evaluates various empirical and physical models from different researchers for the assessment of the material embrittlement.The study proposes strain-rate sensitivity for the characterization of material embrittlement and the concept of the pseudo embrittlement for material responses to very high strain-rates.A discussion section is arranged to explore the underlying mechanisms of the strain-rate evoked material embrittlement and fragmentation based on dislocation kinetics.

Strain-rate Sensitivity of Aluminum 2024-T6/TiB_2 Composites and Aluminum 2024-T6

Strain-rate sensitivities of 55vol%-65vol% aluminum 2024-T6/TiB2 composites and the corresponding aluminum 2024-T6 matrix were investigated using split Hopkinson pressure bar method. The experimental results showed that 55vol%-65vol% aluminum 2024-T6/TiB2 composites exhibited significant strain-rate sensitivities, which were three times higher than the strain-rate sensitivity of the aluminum 2024-T6 matrix. The strain-rate sensitivity of the aluminum 2024-T6 matrix composites rose obviously with increasing reinforcement content（up to 60%）, which agreed with that from the previous researches. But it decreased as the ceramic reinforcement content reached 65%. After high strain rates compression, a large number of dislocations and micro-cracks were found inside the matrix and the Ti B2 particles, respectively. These micro-cracks can accelerate the brittle fracture of the composites. The aluminum 2024-T6/Ti B2 composites showed various fracture characteristics and shear instability was the predominant failure mechanism under dynamic loading.

A QUASI-FLOW CONSTITUTIVE MODEL WITH STRAIN-RATE DEPENDENCE

In this paper,the proposed is a quasi-flow constitutive model with strain-rate sen- sitivity for elastic plastic large deformation.The model is based on the Quasi-flow Corner theory, and is suitable for the sheet metal forming process simulation with a variable punch machine velocity. Uniaxial tensile tests and deep-drawing tests of a circular blank with square punch are carried out and numerically simulated.The consistency between the experimental and the numerically simulated results shows the validity of the present new constitutive model.

A revisit of strain-rate frequency superposition of dense colloidal suspensions under oscillatory shears

Strain-rate frequency superposition(SRFS) is often employed to probe the low-frequency behavior of soft solids under oscillatory shear in anticipated linear response. However, physical interpretation of an apparently well-overlapped master curve generated by SRFS has to combine with nonlinear analysis techniques such as Fourier transform rheology and stress decomposition method. The benefit of SRFS is discarded when some inconsistencies of the shifted master curves with the canonical linear response are observed. In this work, instead of evaluating the SRFS in full master curves, two criteria were proposed to decompose the original SRFS data and to delete the bad experimental data. Application to Carabopol suspensions indicates that good master curves could be constructed based upon the modified data and the high-frequency deviations often observed in original SRFS master curves are eliminated. The modified SRFS data also enable a better quantitative description and the evaluation of the apparent structural relaxation time by the two-mode fractional Maxwell model.

Effects of Calcium and Yttrium on Microstructure and Mechanical Properties of High Strain-Rate Rolled AZ91D Magnesium Alloy

Effects of calcium( Ca) and yttrium( Y) on microstructure and mechanical properties of high strain-rate rolled AZ91 D magnesium alloy were studied. High strain-rate rolling can improve the strength and plasticity of magnesium alloy sheets.Additions of Ca and Y into AZ91 D can refine grains and modify the size and the distribution of the precipitated phases. After solution treatment( 418 ℃ and 20 h) and high strain-rate rolling( heating at420 ℃ for 10 min firstly and then rolling from 10 mm to 2 mm in thickness via a single pass),the tensile strength of the AZ91 D-0. 2%Ca alloy was 1. 3% higher than that of the AZ91 D-0. 4 D%Y alloy,and the tensile strength of the AZ91 D-0. 2%Ca-0. 4%Y alloy was about 8. 3% and 6. 9% higher than those of the AZ91 D-0. 4%Y and the AZ91 D-0. 2%Ca alloys respectively.

Advanced test methods of material property characterization:high strain-rate testing and experimental simulation of multiaxial stress states

Optimum utilization of the loading capability of engineering materials is an important and active contribution to protect nature's limited resources,and it is the key for economic design methods.In order to make use of the materials' resources,those must be known very well;but conventional test methods will offer only limited informational value.The range of questions raised is as wide as the application of engineering materials,and partially they are very specific.The development of huge computer powers enables numeric modelling to simulate structural behaviour in rather complex loading environments-so the real material behaviour is known under the given loading conditions.Here the art of material testing design starts.To study the material behaviour under very distinct and specific loading conditions makes it necessary to simulate different temperature ranges,loading speeds, environments etc.and mostly there doesn't exist any commonly agreed test standard.In this contribution two popular,non-standard test procedures and test systems will be discussed on the base of their application background,special design features as well as test results and typically gained information:The demand for highspeed tests up to 1000 s^(-1) of strain rate is very specific and originates primarily in the automotive industry and the answers enable CAE analysis of crashworthiness of vehicle structures under crash conditions.The information on the material behaviour under multiaxial loading conditions is a more general one.Multiaxial stress states can be reduced to an equivalent stress,which allows the evaluation of the material's constraint and criticality of stress state.Both discussed examples shall show that the open dialogue between the user and the producer of testing machines allows custom-tailored test solutions.

Dynamic Response of Pultruded Glass-Graphite/Epoxy Hybrid Composites Subjected to Transverse High Strain-Rate Compression Loading

In a previous study, the energy absorption and dynamic response of different combinations of cylindrical fiber-reinforced pultruded hybrid composite samples made of unidirectional glass and graphite fiber/epoxy, were investigated under longitudinal compression loading. It was found that placing glass fibers in the inner core of composites resulted in a higher ultimate compressive strength and specific energy absorption. In this study, the dynamic responses of pultruded glass-graphite/epoxy hybrid specimens with rectangular cross-section subjected to transverse compression loading are reported. Crack initiation and propagation was monitored using a high-speed video camera, and the effects of hybridization were analyzed. It was found that the location of glass or graphite fibers inside the pultruded composites has no significant effect on the ultimate compressive strength under such transverse compression loading. The energy absorption in all the hybrid specimens was almost identical. Graphite/epoxy composite showed higher specific energy absorption due to its lower density, and glass/epoxy composite had the lowest specific energy absorption.

Energy Absorption of Pultruded Glass-Graphite/Epoxy Hybrid Composites under High Strain-Rate Induced Transverse Tension

This paper focuses on the dynamic tensile response of glass-graphite/epoxy composites illustrating improvement in energy absorption through hybridization. The dynamic response and energy absorption characteristics of pultruded hybrid combinations of glass and graphite fibers in an epoxy matrix subjected to induced transverse tension at high strain-rate in a modified Split Hopkinson Pressure Bar (SHPB) apparatus, are presented. Transverse tensile strength was determined by diametral compression of disc samples (Brazilian indirect tensile test method). Diametral crack initiation and strain to failure were monitored with a Shimadzu HPV-2 high-speed video camera at a recording speed of 500,000 fps and Digital Image Correlation (DIC). Adequate measures were taken to ensure that initiation of specimen failure occurred at the exact center of the disc specimen, and propagated through the diameter along the compressive loading axis, for the induced transverse tension tests to be valid. A study of the strength and specific energy absorption demonstrates the benefits of hybridization. Under induced transverse tensile loading condition, the pure glass/epoxy (GL60) exhibited higher strength than pure graphite/epoxy (GR60). Pure graphite/epoxy (GR60) has higher specific energy absorption capacity than pure glass/epoxy (GL60) in transverse tension. Among all hybrids, GR30 has the highest specific energy absorption under transverse tension. Overall, hybrid GL48, with 48% low-cost glass fibers in the inner core and 12% high-cost graphite fibers in outer shell, was found to exhibit better performance under induced transverse tension at high strain-rates, showing the benefits of hybridization.

The relationship between age,acceptable noise level,and listening effort in middle-aged and older-aged individuals

Objective:The purpose of the study was to evaluate listening effort in adults who experience varied annoyance towards noise.Materials and methods:Fifty native Kannada-speaking adults aged 41e68 years participated.We evaluated the participant's acceptable noise level while listening to speech.Further,a sentence-final wordidentification and recall test at 0 dB SNR(less favorable condition)and 4 dB SNR(relatively favorable condition)was used to assess listening effort.The repeat and recall scores were obtained for each condition.Results:The regression model revealed that the listening effort increased by 0.6%at 0 dB SNR and by 0.5%at 4 dB SNR with every one-year advancement in age.Listening effort increased by 0.9%at 0 dB SNR and by 0.7%at 4 dB SNR with every one dB change in the value of Acceptable Noise Level(ANL).At 0 dB SNR and 4 dB SNR,a moderate and mild negative correlation was noted respectively between listening effort and annoyance towards noise when the factor age was controlled.Conclusion:Listening effort increases with age,and its effect is more in less favorable than in relatively favorable conditions.However,if the annoyance towards noise was controlled,the impact of age on listening effort was reduced.Listening effort correlated with the level of annoyance once the age effect was controlled.Furthermore,the listening effort was predicted from the ANL to a moderate degree.

An Artificial Neural Network-Based Model for Effective Software Development Effort Estimation

In project management,effective cost estimation is one of the most cru-cial activities to efficiently manage resources by predicting the required cost to fulfill a given task.However,finding the best estimation results in software devel-opment is challenging.Thus,accurate estimation of software development efforts is always a concern for many companies.In this paper,we proposed a novel soft-ware development effort estimation model based both on constructive cost model II(COCOMO II)and the artificial neural network(ANN).An artificial neural net-work enhances the COCOMO model,and the value of the baseline effort constant A is calibrated to use it in the proposed model equation.Three state-of-the-art publicly available datasets are used for experiments.The backpropagation feed-forward procedure used a training set by iteratively processing and training a neural network.The proposed model is tested on the test set.The estimated effort is compared with the actual effort value.Experimental results show that the effort estimated by the proposed model is very close to the real effort,thus enhanced the reliability and improving the software effort estimation accuracy.

父母心理控制与青少年外化问题行为的关系:意志控制和越轨同伴交往的链式中介作用

本研究以生态系统理论和选择理论为基础,考察意志控制、越轨同伴交往在父母心理控制和外化问题行为关系中的链式中介效应。研究使用父母心理控制问卷、意志控制问卷、越轨同伴交往问卷和外化问题行为问卷对1053名中学生进行了调查。结果显示:在控制了人口学变量(性别、年龄以及家庭经济社会地位)后,(1)越轨同伴交往在父母心理控制与青少年外化问题行为之间的中介作用显著;(2)意志控制在父母心理控制与青少年外化问题行为间的中介作用不显著;(3)意志控制和越轨同伴交往在父母心理控制与青少年问题行为之间的链式中介作用显著;(4)中介效应在男女生中呈现相似的显著性模式、在不同学段中不存在显著差异。这些结果对于青少年外化问题的预防与干预提供了一定的启示。

地方财力冲击下的企业纳税遵从:征管效应还是迎合效应?

利用2010—2015年中国税收调查数据,以国际石油价格暴跌作为外生冲击,构建强度双重差分(DID)模型探究地方财力冲击对企业纳税遵从行为的因果效应。研究发现:“压力型”财政冲击下,企业纳税遵从显著提升;政府为弥补财力缺口,倾向于加强对小微企业的纳税监管,但是财力不足反而刺激了少数民族地区企业的避税动机。从影响机制来看,财政压力下,地方政府会提高征税努力并加强税收监管,同时企业也会采取策略性行为迎合政府财政需求,两种渠道共同抑制了企业避税行为。进一步分析表明,地方财力冲击所激发的征管效应与迎合效应,提升了地区行业间税负公平性。

基于效果定价模式的网络直播广告定价决策研究

网络直播广告作为一种新型营销方式快速发展,优化直播广告运营主体努力水平及定价策略是一项值得深入研究的课题。本文基于广告投放效果的两种定价模式,构建了包含两个广告商和一个主播的网络直播广告定价决策模型,探索广告商与主播的最优努力水平选择及广告定价策略。研究发现:CPW(cost per watch)定价模式下,广告商承担了消费者是否购买的不确定性风险,当消费者敏感性系数偏低时,广告商会提交较低的出价,且B/D两类广告商赢得竞拍的概率相等;对比CPW模式,在CPA(cost per action)定价模式下广告商的努力水平更低,且CPA定价模式中B型(品牌型)广告商赢得竞拍的概率更大,但赢得竞拍的广告商边际利润往往较低;与广告商相反,主播在CPA定价模式下的收益大于CPW,且随消费者敏感性系数的增加,两种定价模式下的收益差逐渐增大;CPW定价模式下预期观看直播的用户量和购买率均高于CPA,网络直播市场倾向于从CPW广告定价合同中获得较大收益。

关于水价、水权、水资源税费改革协同发力的思考

运用系统思维,深化水价形成机制、水权及水资源税改革,促进协同发力,是当前和今后一个时期深化水利改革的重点任务。文章在总结改革进展、分析新形势新要求的基础上,对水价、水权、水资源税费的基本属性、改革目的、重点内容进行理论解析,分析了三者间的耦合关系,提出了水价、水权、水资源税费改革协同发力的总体考虑和相关建议。

基于在线评论的服装供应链的生产努力投入策略

考虑消费者购买意愿受在线评论与生产努力的共同影响,构建了由服装制造商、电商平台和消费者组成的服装供应链模型,重点探讨了集中决策模型和分散决策模型下在线评论和生产努力等因素对各参与方利润的影响,并引入“成本分担+收益共享”组合契约来实现供应链的协调。结果表明:集中决策和分散决策的最优解均与生产努力偏好系数呈正相关;受利益驱使,分散决策时的生产努力往往低于集中决策时的生产努力;组合契约模式下,契约参数的取值与批发价格的取值范围有关,在契约参数取值范围内,“成本分担+收益共享”组合契约能实现供应链的协调。研究结果为服装制造商和电商平台销售决策提供借鉴,可提高消费者满意度和市场竞争力。

价格竞争、保鲜努力与农产品电商冷链物流模式演化

科学合理的冷链物流模式是确保农产品电商价格、新鲜度竞争力的关键。针对涉及两农产品电商、电商自营冷链物流和第三方冷链物流商的供应链,构建两电商竞争、第三方冷链物流商主导的Stackelberg博弈模型及两电商冷链物流模式选择的演化博弈模型,并通过仿真揭示交叉价格弹性、新鲜度需求弹性、自营和第三方保鲜投入成本系数对演化路径的影响。研究表明:若交叉价格弹性、新鲜度需求弹性和第三方保鲜投入成本系数分别增大,自营冷链物流为演化稳定策略,电商倾向自营冷链物流。若自营保鲜投入成本系数增大,第三方冷链物流为演化稳定策略,电商倾向与第三方冷链物流商合作。

言语刺激强度对健听者听配能的影响——瞳孔测量研究

目的探究言语刺激强度对健听者听配能的影响。方法选取38例健听成人,采用语速x刺激强度的言语理解测试范式,将瞳孔扩张听配能测量和听觉任务完成准确度及反应速度相结合,观察阈上范围内20 dB SPL的强度变化对听配能和任务表现的影响。结果语速对平均瞳孔扩张有显著影响(P<0.001,η_(p)^(2)=0.618),但刺激强度对平均瞳孔扩张无显著影响(P=0.213,η_(p)^(2)=0.040)。增加言语刺激强度能够显著提升任务反应速度(P=0.043,η_(p)^(2)=0.099),在正常语速下,还能够显著提升言语理解准确度(P<0.001,η_(p)^(2)=0.374)。结论健听人群听觉舒适阈范围内将言语声刺激强度增加20 dB SPL能够提高聆听效率,但该效应可能并不是通过改变可听度或唤醒度,从而影响听配能结果,可能是改变听觉处理速度。

提升监管科技协同创新产出水平的契约激励策略

创新主体的创新努力是提升监管科技协同创新产出水平的关键。已有监管科技的研究主要集中在应用场景上,缺乏深入到监管科技协同创新问题,且监管科技创新产出包括合规科技和狭义监管科技,其有关主体的角色交叉现象导致监管科技协同创新与一般情形的协同创新有很大不同。基于此,根据监管科技创新的供求关系,将创新主体划分为创新研发方和成果应用方,从创新主体追求自身收益最大化的行为逻辑出发,构建协同创新效益模型、开展协同创新激励因子分析,并以双方在协同创新中的努力水平比值作为考察变量,优选提升监管科技协同创新产出水平的激励契约。结果表明:提高创新研发方在协同创新中的地位和收益分配比例能鞭策不够努力的创新主体缩小与努力水平高的创新主体努力水平差距,提高协同创新总体产出水平;将创新研发方的研发人员工资投入等内部管控信号和金融机构的合规成本、监管机构的监管成本变化等市场反馈信号写入成果应用方的委托代理合同,能减少信息不对称、降低契约风险,激励创新研发方按照成果应用方的期望提高创新努力水平,以增加协同创新产出。