A new multi-DOF envelope forming process for fabricating spiral bevel gears with back taper tooth

Spiral bevel gears are critical transmission components,and are widely used in the aerospace field.This paper proposes a new multi-DOF envelope forming process for fabricating spiral bevel gears.Firstly,the multi-DOF envelope forming principle of spiral bevel gears is proposed.Secondly,the design methods for the envelope tool geometry and movement are proposed based on the envelope geometry and movement relationships.Thirdly,the metal flow and tooth filling laws are revealed through 3D FE simulation of the multi-DOF envelope forming process of a typical spiral bevel gear.Fourthly,a new method for separating the envelope tool and the formed spiral bevel gear with back taper tooth is proposed to avoid their interference.Finally,experiments on multi-DOF envelope forming of this typical spiral bevel gear are conducted using new heavy load multi-DOF envelope forming equipment.The simulation and experimental results show the feasibility of the proposed multi-DOF envelope forming process for fabricating spiral bevel gears with back taper tooth and the corresponding process design methods.

Trial application of the envelope method to the potential ambiguity problem

The optical potential ambiguity is a long-standing problem in the analysis of elastic scattering data.For a specific collid-ing system,ambiguous potential families can lead to different behaviors in the nearside and farside scattering components.By contrast,the envelope method can decompose the experimental data into two components with negative and positive deflection angles,respectively.Hence,a question arises as to whether the comparison between the calculated nearside(or farside)component and the derived positive-deflection-angle(or negative-deflection-angle)component can help analyze the potential ambiguity problem.In this study,we conducted a trial application of the envelope method to the potential ambiguity problem.The envelope method was improved by including uncertainties in the experimental data.The colliding systems of 16O+28Si at 215.2 MeV and 12C+12C at 1016 MeV were considered in the analyses.For each colliding system,the angular distribution experimental data were described nearly equally well by two potential sets,one of which is“surface transpar-ent”and the other is refractive.The calculated angular distributions were decomposed into nearside and farside scattering components.Using the improved envelope method,the experimental data were decomposed into the positive-deflection-angle and negative-deflection-angle components,which were then compared with the calculated nearside and farside components.The capability of the envelope method to analyze the potential ambiguities was also discussed.

An envelope-based machine learning workflow for locating earthquakes in the southern Sichuan Basin

The development of machine learning technology enables more robust real-time earthquake monitoring through automated implementations. However, the application of machine learning to earthquake location problems faces challenges in regions with limited available training data. To address the issues of sparse event distribution and inaccurate ground truth in historical seismic datasets, we expand the training dataset by using a large number of synthetic envelopes that closely resemble real data and build an earthquake location model named ENVloc. We propose an envelope-based machine learning workflow for simultaneously determining earthquake location and origin time. The method eliminates the need for phase picking and avoids the accumulation of location errors resulting from inaccurate picking results. In practical application, ENVloc is applied to several data intercepted at different starting points. We take the starting point of the time window corresponding to the highest prediction probability value as the origin time and save the predicted result as the earthquake location. We apply ENVloc to observed data acquired in the southern Sichuan Basin, China, between September 2018 and March 2019. The results show that the average difference with the catalog in latitude, longitude, depth, and origin time is 0.02°,0.02°, 2 km, and 1.25 s, respectively. These suggest that our envelope-based method provides an efficient and robust way to locate earthquakes without phase picking, and can be used in earthquake monitoring in near-real time.

A New Dynamic and Vertical Photovoltaic Integrated Building Envelope for High-Rise Glaze-Facade Buildings

Substantially glazed facades are extensively used in contemporary high-rise buildings to achieve attractive architectural aesthetics.Inherent conflicts exist among architectural aesthetics,building energy consumption,and solar energy harvesting for glazed facades.In this study,we addressed these conflicts by introducing a new dynamic and vertical photovoltaic integrated building envelope(dvPVBE)that offers extraordinary flexibility with weather-responsive slat angles and blind positions,superior architectural aesthetics,and notable energy-saving potential.Three hierarchical control strategies were proposed for different scenarios of the dvPVBE:power generation priority(PGP),natural daylight priority(NDP),and energy-saving priority(ESP).Moreover,the PGP and ESP strategies were further analyzed in the simulation of a dvPVBE.An office room integrated with a dvPVBE was modeled using EnergyPlus.The influence of the dvPVBE in improving the building energy efficiency and corresponding optimal slat angles was investigated under the PGP and ESP control strategies.The results indicate that the application of dvPVBEs in Beijing can provide up to 131%of the annual energy demand of office rooms and significantly increase the annual net energy output by at least 226%compared with static photovoltaic(PV)blinds.The concept of this novel dvPVBE offers a viable approach by which the thermal load,daylight penetration,and energy generation can be effectively regulated.

Hepatitis B surface antigen-negative but hepatitis B envelope antigen-positive false occult hepatitis B virus infection:A case report

BACKGROUND Occult hepatitis B infection(OBI)is characterized by the detection of hepatitis B virus(HBV)DNA in serum(usually HBV DNA<200 IU/mL)or the liver but negativity for hepatitis B surface antigen(HBsAg).The diagnosis of OBI relies on the sensitivity of assays used in the detection of HBV DNA and HBsAg.HBsAg assays with inadequate sensitivity or inability to detect HBV S variants may lead to misdiagnosis of OBI in people with overt HBV infection.CASE SUMMARY We report a HBsAg-negative but hepatitis B envelope antigen-positive patient who had a significant HBV DNA level.The patient was initially diagnosed as having OBI.However,sequence analysis revealed a unique insertion of amino acid residues at positions 120-124 in the S protein,which affects the formation of a disulfide bond that is associated with the formation of a loop.It is well known that there is an overlap between the S protein and Pol protein.We found that this new insertion site occurred in polymerase/reverse transcriptase domain,indi-cating that this insertion might be involved in HBV pathogenicity.The patient was finally diagnosed with a false OBI.CONCLUSION An insertion of amino acid residues at positions 120-124 of the S protein affects the formation of immunodominant epitopes and results in negative HBsAg levels.

砂土应力-应变包络线的唯一性初探

土体循环加卸载外包络线是否具有唯一性在认识土体固有属性上具有重要意义。基于土样全表面变形数字图像测量系统,选用硅微粉和福建标准砂为研究对象,开展了一系列三轴剪切试验和三轴循环加卸载试验,探索等应力幅值、阶梯应力幅值和随机应力幅值循环加卸载下应力-应变外包络线与相应的单调加载应力-应变曲线的一致性。试验结果表明土样在相同密度和围压条件下,单调加载的应力-应变曲线与经历不同循环应力历程的加卸载应力-应变外包络线近似一致,提出了砂土应力-应变外包络线的唯一性;讨论了循环应力历史和应力水平对曲线回归速度的影响以及应力-应变包络线唯一性在建立轴向应变累积模型中的应用。

地铁车站围护结构耦合埋管换热系统运行策略研究

以某地铁车站为研究对象,模拟了其全年动态负荷,确定了地源热泵参数,建立了估算热泵出力及耗电量的参数模型,结合建立的动态换热模型得到了地源热泵系统-埋管阻容耦合仿真模型。以10年为运行周期,计算了埋管出水温度和换热量,分析了不同工况下的换热性能,提出了热泵机组联合冷却塔辅助换热的运行策略。结果显示:围护结构耦合埋管换热系统在长期运行工况下存在机组停机或机组出力不足的情况,当负荷为计算负荷的80%时,可以保证热泵机组出力满足需求;冷却塔联合运行策略在制冷季可以有效降低埋管出水温度,在过渡季冷却塔的免费冷量可以降低埋管出水温度1~2℃,在长期运行工况下具有较好的地温恢复效果。

基于DEA-Malmquist的天津市16家保健定点医院运营效率评价

目的分析干部保健定点医院运营效率,为进一步提升保健医院综合实力提供依据。方法采用数据包络分析(data envelopment analysis,DEA)方法和动态Malmquist指数模型,获取2017—2021年16家保健医院医疗指标,计算全要素生产率指数、生产技术变动指数和技术效率指数,研究医院运营管理效率。结果2017—2021年,只有3家保健医院的全要素生产率呈上升趋势,即第6、第10和第12家医院的均值>1.000,其余医院变化均值均<1.000。全要素生产率均值为0.977,生产技术变动指数为0.983,技术效率变动指数为0.994,运营效率仍有进一步提升空间。结论医院运营效率的下降与生产技术的关系密切,天津市保健医院在2017—2021年的全要素生产率呈下降趋势,这表明生产技术变动和技术效率变动是影响运营效率的主要因素。建议采取加强技术创新投入、人才培养与引进、优化资源配置等措施提高医院运营效率。保健行政部门应做好统筹规划,保证保健医院的有序投入。

徐州地区公共建筑能效测评数据研究

针对徐州地区近十年来公共建筑能效测评数据进行了研究。主要研究了公共建筑节能设计标准的变化、建筑外围护结构保温材料的种类及热工性能、集中空调系统冷热源的类型及其制冷性能、建筑能耗强度及节能率的逐年分布。研究表明,开展能效测评工作,促进了外围护结构热工性能及集中空调系统冷热源制冷性能的提高,建筑能耗强度不断降低,建筑节能水平提升,可助力建筑“双碳”目标实现。

青贮饲料打捆包膜一体机整机结构设计

针对青贮饲料市场需求大及青贮饲料商品化且可自由流通化的发展方向,为适应青贮饲料发展趋势,创新研发了一种青贮饲料打捆包膜一体机。分析研究了饲料传送技术、下网技术、打捆技术、包膜技术和关键机构部件,并利用Autocad、SolidWorks等软件对关键工作部件和整机结构进行绘制,设计出一种可高效率实现青贮饲料打捆包膜于一体的整机;同时,通过试验验证了该机的可行性。该机对提高农民收入、提升青贮饲料利用率,以及推广饲料青贮技术等具有重要现实意义。

Comparative Studies on the Fine Structure and Elemental Composition of Envelopes of Trachelomonas and Strombomonas (Euglenophyta)

Fine structure and elemental composition of envelopes of 10 taxa of Trachelomonas and Strombomonas from natural freshwater bodies in China were studied and phylogeny of both genera were discussed. The results indicate that iron (Fe) and silicon (Si) are the primary mineral elements of the envelopes. Composition of mineral elements was uncorrelated with envelope color, however, it was highly correlated with the microarchitecture of the envelopes. Content of Si was higher than that of Fe in all species of Strombomonas and some species of Trachelomonas with rough surface. In most species of Trachelomonas, especially those with dense and smoothy surface, content of Fe was higher than that of Si. Based on the above results, we propose to assign those species of Strombomonas into Trachelomonas and consider them as a group of the latter. These species were the most primitive among the group with envelopes in Euglenaceae.

Elastic envelope inversion using multicomponent seismic data with filtered-out low frequencies

The absence of low-frequency information in seismic data is one of the most difficult problems in elastic full waveform inversion. Without low-frequency data, it is difficult to recover the long-wavelength components of subsurface models and the inversion converges to local minima. To solve this problem, the elastic envelope inversion method is introduced. Based on the elastic envelope operator that is capable of retrieving low- frequency signals hidden in multicomponent data, the proposed method uses the envelope of multicomponent seismic signals to construct a misfit function and then recover the long- wavelength components of the subsurface model. Numerical tests verify that the elastic envelope method reduces the inversion nonlinearity and provides better starting models for the subsequent conventional elastic full waveform inversion and elastic depth migration, even when low frequencies are missing in multicomponent data and the starting model is far from the true model. Numerical tests also suggest that the proposed method is more effective in reconstructing the long-wavelength components of the S-wave velocity model. The inversion of synthetic data based on the Marmousi-2 model shows that the resolution of conventional elastic full waveform inversion improves after using the starting model obtained using the elastic envelope method. Finally, the limitations of the elastic envelope inversion method are discussed.

Injective Envelopes of a Hilbert C~*Module

As in homology, the notion of injectivity is introduced in the category whose objects are Hilbert C * module over a C * algebra and whose morphism are bounded module operators. The definition of injective envelopes of an extension of a Hilbert C * modules over a C * algebra is introduced, and is characterized in terms of the injectivity and essence. It is shown that every Hilbert C * module has a unique (up to H isometrics) injective envelope if it exists. It is also shown that an extension of a Hilbert C * module is an injective envelope if and only if it is an injective and essential extension. Moreover, every Hilbert C * module over a W * algebra has a unique (up to H isometrics) injective envelope and the injective envelope of a Hilbert C * module H is maximal essential extension of H .

Enveloping algebras of generalized H-Hom-Lie algebras

Let H be a Hopf algebra and HYD the Yetter- Drinfeld category over H. First, the enveloping algebra of generalized H-Hom-Lie algebra L, i.e., Hom-Lie algebra L H in the category HYD, is constructed. Secondly, it is obtained that U（L） = T（ L）/L where I is the Hom-ideal of T（L） generated by {ll＇-l_（（-1））·l＇l_0-[l,l＇]｜l,l＇∈L}, and u： L,T（L）/I is the canonical map. Finally, as the applications of the result, the enveloping algebras of generalized H-Lie algebras, i.e., the Lie algebras in the category MyDn and the Hom-Lie algebras in the category of left H-comodules are presented, respectively.

基于SM2和DNA的图像加密算法

近年来,随着互联网的全面普及,公民对信息安全和隐私保护提出了新的更高的要求,为了保护公民的数据安全,并且满足“打赢新时代网络战争”的要求,对图像加密算法的研究与实现进行深入的研究,提出了一种基于国密SM2数字信封和脱氧核糖核酸(Deoxyribonucleic acid,DNA)编码的图像加密技术,将图像编码技术、公钥技术、口令保护技术相结合.在该算法中,通过使用Python重点实现了密钥空间的复杂性、图像的鲁棒性、随机性、低相关性,同时对图像的直方图进行了分析,研究结果表明,在实现公钥加密算法国产化替代的同时,增强了加密的安全性.

基于包络互相关定位方法的积石山M_(S)6.2地震前超低频地震研究

利用包络互相关方法对积石山M_(S)6.2地震前的超低频地震进行定位。先在较大范围内进行初步定位,然后在较小范围内进行精确定位。通过增加或减少震源不同方位的台站数量进行分析,结果显示,台站在各个方位上的均匀分布至关重要,可以有效减小定位误差。定位结果表明,积石山地震前的超低频地震主要分布在断裂带附近,分布方位和断层方向保持一致。

我国煤炭上市公司经营效率评价及对策研究

为提高我国煤炭上市公司经营效率,促进煤炭行业高质量、可持续发展,文章采用DEA-BCC-I模型对32家煤炭上市公司2022年的经营效率进行分析评价。研究表明:32家煤炭上市公司的综合技术效率平均值为0.521,整体水平较低,DEA有效的仅有潞安环能、山西焦化、昊华能源、陕西煤业、宝丰能源五家公司;技术水平低下是经营效率无效的主要抑制原因,投入规模是次要抑制原因。冗余分析表明,余下27家DEA无效的煤炭上市公司中存在投入资源冗余的情况。建议采取强化技术创新能力、优化企业经营规模、提高投入要素的匹配度、深化企业合作等针对性措施,以提高企业经营效率。

基于改进EWT的病理嗓音检测

特征提取是病理嗓音信号检测中至关重要的步骤。针对经验小波变换(Empirical Wavelet Transform,EWT)在处理复杂频谱信号时的频带划分问题,提出一种基于倒谱包络线改进的EWT,自适应地划分元音/a/的第一和第二共振峰频带,通过计算第一和第二共振峰频带内不同帧之间的皮尔逊相关系数,获得EWTPCC(Empirical Wavelet Transform Pearson Correlation Coefficient)特征。实验结果表明,EWTPCC特征结合支持向量机(Support Vector Machines,SVM)的方法,在萨尔布吕肯语料库(Saarbrücken Voice Database,SVD)中的识别率达到87.65%,可以有效地区分正常嗓音与病理嗓音。

医药院校科技成果研发及转化效率研究

目的对入选“双一流”建设的10所医药院校及除上述院校外五年总科技量值排名前10的医药院校进行成果研发和转化效率的测算和分析,为提高此类院校科技成果转化管理水平提供对策建议。方法使用传统数据包络分析模型和超效率数据包络分析模型测算所选医药院校科技成果研发和转化两阶段效率值;使用Malmquist指数模型测算医药院校整体科技成果转化效率变化情况。结果20所医药院校在成果研发阶段的产出效率高于成果转化阶段,其中有5所院校在成果研发阶段处于产出有效状态;在成果转化阶段,共2所院校处于产出有效状态。医药院校的整体科技成果转化效率在稳步提升。结论中国医药院校应结合实际,全面加强产学研有效合作;建立成果转化专业队伍;健全成果转化管理体系;完善人才梯队建设,提高科技成果转化效率。

基于数据清洗与个性化联邦学习的风电功率预测研究

针对风电数据的波动性及数据质量问题,提出了一种基于数据清洗与串联门控循环单元(Gated recurrent unit,GRU)及注意力机制(Attention,Att)的风电功率预测模型,并通过联邦学习实现区域模型参数传递。引入Moreau信封作为联邦学习的正则化损失函数,提出了个性化联邦学习框架(Personalized fderated larning with Moreau evelopes,PFedMe)。兼顾数据安全和预测性能的双重需求,为新建电厂在数据缺失条件下预测风电功率提供了方案。最后,采用百度动态空间风电功率预测挑战赛数据集进行实验验证,结果表明:所提方案在满足隐私安全约束下实现了高效模型训练与预测性能提升。