The Additive-multiplicative Hazards Model for Multiple Type of Recurrent Gap Times

Recurrent event gap times data frequently arise in biomedical studies and often more than one type of event is of interest. To evaluate the effects of covariates on the marginal recurrent event hazards functions, there exist two types of hazards models： the multiplicative hazards model and the additive hazards model. In the paper, we propose a more flexible additive-multiplicative hazards model for multiple type of recurrent gap times data, wherein some covariates are assumed to be additive while others are multiplicative. An estimating equation approach is presented to estimate the regression parameters. We establish asymptotic properties of the proposed estimators.

An Additive Hazards Model for Clustered Recurrent Gap Times

In this article, clustered recurrent gap time is investigated. A marginal additive haz- ards model is proposed without specifying the association of the individuals within the same cluster. The relationship among the gap times for the same individual is also left unspecified. An estimating equation-based inference procedure is developed for the model parameters, and the asymptotic proper- ties of the resulting estimators are established. In addition, a lack-of-fit test is presented to assess the adequacy of the model. The finite sample behavior of the proposed estimators is evaluated through simulation studies, and an application to a clinic study on chronic granulomatous disease （CGD） is illustrated.

The Proportional Hazards Model for Multiple Type Recurrent Gap Times

Recurrent events data and gap times between recurrent events are frequently encountered in many clinical and observational studies,and often more than one type of recurrent events is of interest.In this paper,we consider a proportional hazards model for multiple type recurrent gap times data to assess the effect of covaxiates on the censored event processes of interest.An estimating equation approach is used to obtain the estimators of regression coefficients and baseline cumulative hazard functions.We examine asymptotic properties of the proposed estimators.Finite sample properties of these estimators are demonstrated by simulations.

On a General Class of Semiparametric Hazards Regression Models for Recurrent Gap Times

In the article,we investigate a general class of semiparametric hazards regression models for recurrent gap times.The general class includes the proportional hazards model,the accelerated failure time model and the accelerated hazards models as special cases.The model is flexible in modelling recurrent gap times since a covariate effect is identified as having two separate components,namely a time-scale change on hazard progression and a relative hazards ratio.In order to infer the model parameters,the procedure is proposed based on estimating equations.The asymptotic properties of the proposed estimators are established and the finite sample properties are investigated via simulation studies.In addition,a lack of fit test is presented to assess the adequacy of the model and an application of data from a bladder cancer study is reported for illustration.

Quantification constraints on time gap for comagmatic gold deposits:Evidence from chronological statistics

The time gap between diagenesis and mineralization (TGDM) for comagmatic gold deposits (CGD) plays an important role in confirming the genetic relationship between gold deposits and their related intrusions. With the help of preciously published isotopic ages of some typical gold deposits and their related rocks in China,the authors have discussed and quantified the distribution characteristics and scope of the TGDM. Statistical analyses and Kolmogorov tests showed that mineralizing events are either contemporaneous with or slightly postdate their cognate magma. The TGDM conforms with normal distributions at a 0.05 confidence level and clusters between 0 and 16.0 Ma with a mean of 7.0 Ma. Thus,if the TGDM of CGD is less than 16.0 Ma,it is reasonable to consider,with the aid of other evidence,the possibility of its comagmatic genetic affiliation. The authors also emphasized that to get a precise time gap it is necessary to strengthen the diagenesis-mineralization geological background of the deposits studied,and to pay attention to the study of time gap in combination with trace elements and isotope tracing.

Time-dependent Ginzburg–Landau equations for multi-gap superconductors

We numerically solve the time-dependent Ginzburg–Landau equations for two-gap superconductors using the finite-element technique. The real-time simulation shows that at low magnetic field, the vortices in small-size samples tend to form clusters or other disorder structures. When the sample size is large, stripes appear in the pattern. These results are in good agreement with the previous experimental observations of the intriguing anomalous vortex pattern, providing a reliable theoretical basis for the future applications of multi-gap superconductors.

Gap solitons in parity time complex superlattice with dual periods

A theory is presented to investigate the existence and propagation stability of gap solitons in a parity-time （PT） com- plex superlattice with dual periods. In this superlattice, the real and imaginary parts are both in the form of superlattices with dual periods. In the self-focusing nonlinearity, PT solitons can exist in the semi-infinite gap. However, only those gap solitons with low powers can propagate stably, whereas the high-power solitons present periodic oscillation and simultane- ously suffer energy decay. In the self-defocusing nonlinearity, PT solitons only exist in the first gap and all these solitons are stable.

gap度量下线性时变系统的最优鲁棒性

本文主要研究了离散时间线性时变(Linear time-varying,LTV)系统中基于gap度量的鲁棒性优化问题,该问题涉及最大稳定性边缘的计算。借助套代数中算子的内外因子分解方法,推导出了最大稳定性边缘的公式,并证明了一致渐近时不变LTV系统最优控制器的存在性。

基于声子晶体的周期性基础机器振动波衰减性能分析

文章利用COMSOL多物理场程序计算不同参数周期性基础的衰减域特性,探讨周期性基础对机器振动波的衰减和阻隔作用。利用商业有限元ABAQUS软件建立周期性基础机器振动有限元模型,对不同厚度、材料的周期性基础模型进行频域分析,得到周期性基础的频散关系;通过时程分析研究周期性基础机器的动力响应和振动衰减效果。结果表明:当输入波的频率处于周期性基础频率带隙内时,可以有效地减小上部机器的动力响应;当输入波的主频处于周期性基础频率带隙外时,无法减小上部机器的动力响应;不同厚度和材料的周期性基础的带隙以及对于上部机器振动的减振效果不同。研究结果为周期性基础在工业厂房机器减振中的应用提供了新的思路和方法。

珍妮特·温特森《时间之间》中的音乐母题

珍妮特·温特森以莎士比亚的《冬天的故事》为原型创作了《时间之间》。小说不仅与原剧形成明显的互文关系,还与音乐紧密关联,因为该小说文本有大量的音乐在场。对音乐母题的探讨有益于该小说的研究,但目前国内外学者对此研究甚少。用文本细读的方法,梳理《时间之间》中与音乐相关的人物、乐器及演奏技法、音乐的传播媒介、音乐史等音乐母题的具体呈现,旨在探讨音乐母题在小说文本建构和生成中发挥的推动主要情节发展、表达人物基本情绪、治愈人物心理创伤等作用,阐明音乐母题对表达传统主题的时代新意具有价值,以期从被忽略的音乐母题的视角来丰富对小说的研究。

数字经济与技能工资差距——基于CFPS的微观证据

随着引领新一轮科技革命和产业升级的数字技术发展,数字经济必将对中国的就业和收入分配格局产生重大影响,使技能工资差距呈现新特征。通过测度2018年中国各行业的数字经济发展水平,借助普通最小二乘法、无条件分位数回归与Oaxaca-Blinder分解等方法,考察数字经济发展对技能工资差距的影响及其作用机制。结果发现:(1)数字经济显著提高了低技能劳动者工资收入,且能缩小低技能群体和高技能群体内部中低收入差距;(2)数字经济能通过就业创造效应和时间投入效应为劳动者提供更多就业机会和就业岗位,提高工作强度,缩小技能工资差距,但职位晋升效应难以充分发挥;(3)数字经济对不同行业部门和不同社会资本群体的技能工资差距的影响存在显著的差异性。据此提出继续推进数字技术发展、积极探索数字经济背景下对高收入的规范与调节路径、完善对低技能群体的劳动权益保障体系、加强学习型社会建设,并以数字化改革推动公共服务高质量发展和实现基本公共服务均等化等政策建议。

有效-有为-有爱的三次分配制度构建——基于广东省居民收入差距拉大的分析

收入差距缩小是共同富裕的重要标志之一,优化收入分配制度是缩小收入差距的重要举措。通过分析2013—2022年广东省居民收入数据发现:行业收入差距明显;城乡居民可支配收入差距变大;珠三角与粤东西北地区的人均可支配收入差距进一步扩大。这种现象主要是受统一要素市场不成熟、转移支付与税制建设不足以及社会互助激励欠佳复合影响的结果。未来应促进要素自由流动和强化规则衔接来提高初次分配份额;延续提低-扩中-调高思路,分步骤优化再分配机制;弘扬广济善助的美德,加大第三次分配力度,最终形成有效-有为-有爱的三次分配制度。

窄间隙GMAW咬边缺陷的电弧声信号特征分析与识别

针对窄间隙熔化极气体保护焊(Gas Metal Arc Welding,GMAW)焊道侧壁处局部咬边缺陷检测困难的问题,提出了一种基于电弧声信号特征提取与处理的咬边缺陷在线检测方法。通过分析正常、临界咬边和咬边这3种焊接状态的电弧形态和电弧声信号特征,证实坡口侧壁引起的电弧形态变化是影响电弧声信号变化的重要因素。在此基础上采用小波包时频分析,同时引入特征类间标准差作为评价指标,确定了能有效识别3种焊接状态的敏感特征。采用Sigmoid支持向量机和五折交叉验证建立预测模型,实验结果表明该模型能较好地实现3种焊接状态的预测分类,识别准确率达到96.0%。

考虑投资不确定性的项目组合选择IGDT模型

受政策的改变以及对新兴领域项目投资缺少足够认知的影响,管理者的项目投资行为往往呈现一定的不确定性。针对企业管理者在进行项目组合投资决策时存在一定风险偏好的情况,本文基于信息间隙决策理论(Information Gap Decision Theory,IGDT),引入净现值偏差系数对管理者的风险偏好进行描述,构建了考虑投资不确定性的项目组合选择新模型。采用包络约束对投资金额不确定性进行描述,给出风险规避与机会寻求两种策略下的项目组合选择IGDT优化模型,并将其转化成单层规划模型进行求解。通过算例仿真,验证了模型的有效性。结果表明:IGDT优化模型不仅满足了管理者投资的预期净现值要求,而且给出了最优的投资金额与项目选择结果。本文构建模型可以为管理者在项目风险管控和资金管理优化方面提供参考。

Examining the characteristics between time and distance gaps of secondary crashes

Understanding the characteristics of time and distance gaps between the primary(PC)and secondary crashes(SC)is crucial for preventing SC ccurrences and improving road safety.Although previous studies have tried to analyse the variation of gaps,there is limited evidence in quantifying the relationships between different gaps and various influential factors.This study proposed a two-layer stacking framework to discuss the time and distance gaps.Specifically,the framework took random forests(RF),gradient boosting decision tree(GBDT)and eXtreme gradient boosting as the base classifiers in the first layer and applied logistic regression(LR)as a combiner in the second layer.On this basis,the local interpretable model-agnostic explanations(LIME)technology was used to interpret the output of the stacking model from both local and global perspectives.Through SC dentification and feature selection,346 SCs and 22 crash-related factors were collected from California interstate freeways.The results showed that the stacking model outperformed base models evaluated by accuracy,precision,and recall indicators.The explanations based on LIME suggest that collision type,distance,speed and volume are the critical features that affect the time and distance gaps.Higher volume can prolong queue length and increase the distance gap from the SCs to PCs.And collision types,peak periods,workday,truck involved and tow away likely induce a long-distance gap.Conversely,there is a shorter distance gap when secondary roads run in the same direction and are close to the primary roads.Lower speed is a significant factor resulting in a long-time gap,while the higher speed is correlated with a short-time gap.These results are expected to provide insights into how contributory features affect the time and distance gaps and help decision-makers develop accurate decisions to prevent SCs.

分置式斯特林制冷机耦合间隙对探测器性能的影响

分置式斯特林制冷机作为红外探测器组件的重要组成部分,在实际应用中对红外探测器组件的性能影响较大。其中,分置式斯特林制冷机与杜瓦耦合时的耦合间隙是对红外探测器组件的性能影响最大的因素之一。因此针对二者的耦合间隙对探测器性能的影响进行了实验研究。当芯片温度为75 K且制冷机的冷头温度为70 K时,模拟仿真冷指与杜瓦的变形量,耦合间隙变形为0.0096 mm。低温环境对制冷机冷指与杜瓦变形的影响较小,可以忽略冷指与杜瓦变形对耦合间隙的影响。实验结果表明,红外探测器组件的降温时间随耦合间隙的增大而逐渐增大。随着时间的逐渐增大,不同耦合间隙对应的直流电流也各不相同。同一时刻下,耦合间隙越小,直流电流就越小。二极管电压随时间的增加呈现出逐渐增大并逐渐平稳的状态。在达到控温状态前,同一时刻下,耦合间隙越小,二极管电压越大。

Research on Multiple Access Algorithms for Wireless Network

Nodes in the communication network mainly depend on the Media Access Control(MAC)layer protocol design.To ensure the MAC protocol achieves high throughput,low latency,and high service quality,this paper designed a“centralized-distribution”system MAC protocol combined with a slot allocation algorithm.This allows it to quickly adapt to the topology changes in the network and the overall network frame structure.For the centralized time slot allocation,since the system’s frame structure changes across the entire network,the root node must gather information from other nodes.This ensures that the root node can collect the latest topology information when the network topology changes and subsequently adjust the frame structure of the whole network for the distributed time slot allocation.The simulation results show that the adaptive time-division multiple access mechanism can quickly adapt to changes in topology and the network’s frame structure.It enables adaptive changes in node transmission times,ensures the rapid transmission and circulation of large-capacity data between nodes,and improves transmission efficiency.

机器人应用对企业内部薪酬差距的影响——基于多时点DID的实证

本文基于中国A股制造业上市公司数据,采用基于倾向得分匹配的多期双重差分法(PSM-DID)考察机器人应用对企业内部薪酬差距的影响及作用机制。结果发现,机器人应用能够显著缩小企业内部薪酬差距,在更换解释变量等一系列稳健性检验后结果依然稳健。机器人应用可通过促进企业创新及抑制盈余管理行为缩小企业内部薪酬差距,异质性检验结果表明机器人应用对企业内部薪酬差距的影响在规模更大、资本密集度更高的企业中更显著。进一步研究发现,机器人应用对企业内部薪酬差距的缩小显著表现为降低高管超额薪酬进而缩小企业内超额薪酬差距。本文研究为探索企业内部薪酬差距的治理机制提供了新视角,为我国在推动制造业转型升级的同时实现收入公平提供了重要参考。

大鼠脑干损伤GAP-43、NOS3、HIF-1α的表达及其表达时相的相关性研究

目的探讨大鼠脑干损伤后组织的GAP-43、NOS3、HIF-1α的表达特点及其与不同损伤时间的相关性。方法雄性Wistar大鼠55只,采用撞击法制作大鼠机械性脑干损伤动物模型,采集损伤后1h～14d内9个不同时间点的脑干组织,另设正常对照组及假损伤组。采用免疫组化SP法检测GAP-43、NOS3和HIF-1α不同时间点的表达变化及其时相的相关性。结果 GAP-43阳性表达在脑干损伤后3h表达增高,并与正常对照组和假损伤组比较差异均具有统计学意义。7d达高峰,并与正常对照组、假损伤组及邻近上组比较差异具有统计学意义。14d降至正常,与正常对照组及假损伤组比较差异无统计学意义;NOS3在损伤后1h表达增加,并与正常对照组和假损伤组比较差异具有统计学意义。9h达到高峰,并与正常对照组、假损伤组及邻近上组比较差异具有统计学意义,7d表达至正常,与正常对照组及假损伤组比较差异无统计学意义;HIF-1α在损伤后3h阳性表达增加,并与正常对照组和假损伤组比较差异具有统计学意义,24h达到高峰,并与正常对照组、假损伤组及邻近上组比较差异具有统计学意义,7d降至正常,与正常对照组及假损伤组比较差异无统计学意义。结论大鼠脑干损伤后GAP-43、NOS3、HIF-1α表达均有上调,且各自呈一定的时序性变化规律,可望为法医学脑干损伤早期时间的推断提供参考。

Potentials of GaP as millimeter wave IMPATT diode with reference to Si,GaAs and GaN

This paper presents the simulation results of DC,small-signal and noise properties of GaP based Double Drift Region( DDR) Impact Avalanche Transit Time( IMPATT) diodes. In simulation study we have considered the flat DDR structures of IMPATT diode based on GaP,GaAs,Si and GaN( wurtzite,wz) material. The diodes are designed to operate at the millimeter window frequencies of 94 GHz and 220 GHz. The simulation results of these diodes reveal GaP is a promising material for IMPATT applications based on DDR structure with high break down voltage( V_B) as compared to Si and GaAs IMPATTs. It is also encouraging to worth note GaP base IMPATT diode shows a better output power density of 4. 9 × 10~9 W/m^2 as compared to Si and GaAs based IMPATT diode. But IMPATT diode based on GaN( wz) displays large values of break down voltage,efficiency and power density as compared to Si,GaAs and GaP IMPATTs.