Analysis of dynamic characteristics of self-aligning ball bearing

A dynamics model of the self-aligning ball bearing is proposed based on the Jones-Harris method （JHM）, and a computer program is developed to solve the equations by using the Newton-Raphson method. A parametric analysis of the centrifugal force and the gyroscopic moment, the contact loads, the contact angles, the radial deformation and the radial stiffness is carried out. The analytical results show that the applied loads and the rotational speed are two main factors that can influence the distributions of the contact loads and values of the contact angles. The centrifugal force and the gyroscopic moment increase with the increase in the rotational speed, resulting in the decrease of the inner raceway contact load and the increase of the outer raceway contact load. The outer raceway contact angle increases under the centrifugal force; on the contrary, the inner raceway contact angle decreases. Furthermore, the differences between the inner and the outer contact angles increase with the increase in the rotational speed. The higher rotational speed results in the decrease in radial stiffness for the self-aligning ball bearing, and the raceway curvature coefficient, to some extent, also influences the radial stiffness.

A novel self-alignment method for high precision silicon diffraction microlens arrays preparation and its integration with infrared focal plane arrays

Silicon(Si)diffraction microlens arrays are usually used to integrating with infrared focal plane arrays(IRFPAs)to improve their performance.The errors of lithography are unavoidable in the process of the Si diffrac-tion microlens arrays preparation in the conventional engraving method.It has a serious impact on its performance and subsequent applications.In response to the problem of errors of Si diffraction microlens arrays in the conven-tional method,a novel self-alignment method for high precision Si diffraction microlens arrays preparation is pro-posed.The accuracy of the Si diffractive microlens arrays preparation is determined by the accuracy of the first li-thography mask in the novel self-alignment method.In the subsequent etching,the etched area will be protected by the mask layer and the sacrifice layer or the protective layer.The unprotection area is carved to effectively block the non-etching areas,accurately etch the etching area required,and solve the problem of errors.The high precision Si diffraction microlens arrays are obtained by the novel self-alignment method and the diffraction effi-ciency could reach 92.6%.After integrating with IRFPAs,the average blackbody responsity increased by 8.3%,and the average blackbody detectivity increased by 10.3%.It indicates that the Si diffraction microlens arrays can improve the filling factor and reduce crosstalk of IRFPAs through convergence,thereby improving the perfor-mance of the IRFPAs.The results are of great reference significance for improving their performance through opti-mizing the preparation level of micro nano devices.

First demonstration of a self-aligned p-channel GaN back gate injection transistor

In this study,we present the development of self-aligned p-channel Ga N back gate injection transistors(SA-BGITs)that exhibit a high ON-state current.This achievement is primarily attributed to the conductivity modulation effect of the 2-D electron gas(2DEG,the back gate)beneath the 2-D hole gas(2DHG)channel.SA-BGITs with a gate length of 1μm have achieved an impressive peak drain current(I_(D,MAX))of 9.9 m A/mm.The fabricated SA-BGITs also possess a threshold voltage of 0.15 V,an exceptionally minimal threshold hysteresis of 0.2 V,a high switching ratio of 10~7,and a reduced ON-resistance(RON)of 548Ω·mm.Additionally,the SA-BGITs exhibit a steep sub-threshold swing(SS)of 173 mV/dec,further highlighting their suitability for integration into Ga N logic circuits.

Type Synthesis of Self-Alignment Parallel Ankle Rehabilitation Robot with Suitable Passive Degrees of Freedom

The current parallel ankle rehabilitation robot(ARR)suffers from the problem of difficult real-time alignment of the human-robot joint center of rotation,which may lead to secondary injuries to the patient.This study investigates type synthesis of a parallel self-alignment ankle rehabilitation robot(PSAARR)based on the kinematic characteristics of ankle joint rotation center drift from the perspective of introducing"suitable passive degrees of freedom(DOF)"with a suitable number and form.First,the self-alignment principle of parallel ARR was proposed by deriving conditions for transforming a human-robot closed chain(HRCC)formed by an ARR and human body into a kinematic suitable constrained system and introducing conditions of"decoupled"and"less limb".Second,the relationship between the self-alignment principle and actuation wrenches(twists)of PSAARR was analyzed with the velocity Jacobian matrix as a"bridge".Subsequently,the type synthesis conditions of PSAARR were proposed.Third,a PSAARR synthesis method was proposed based on the screw theory and type of PSAARR synthesis conducted.Finally,an HRCC kinematic model was established to verify the self-alignment capability of the PSAARR.In this study,93 types of PSAARR limb structures were synthesized and the self-alignment capability of a human-robot joint axis was verified through kinematic analysis,which provides a theoretical basis for the design of such an ARR.

Factors Affecting Cotrimoxazole Prophylactic Therapy Compliance in HIV Patients Attending a Care and Treatment Clinic at Bugando Medical Centre in Mwanza, Tanzania

Introduction: Cotrimoxazole Prophylactic Therapy (CPT) compliance lowers the risk of opportunistic infections and other Acquired Immune Deficiency Syndrome (AIDS)-related diseases. The aim of this study was to examine factors that influence compliance with CPT among HIV patients in the Care and Treatment Clinic (CTC) at Bugando Medical Centre (BMC) in Mwanza, Tanzania. Methods: A descriptive cross-sectional study was conducted at the BMC between April 1, 2021, and June 30, 2021. Data were collected using face-to-face interviews and a semi-structured questionnaire. Data are presented in frequency, percentages, and cross-tabulation tables. A P-value of less than 0.05 was considered statistically significant. Results: The prevalence of compliance with CPT by self-reported measurement was 158 (63.7%). Most CPT-compliant participants were more likely to have a spouse who is familiar with CPT, have a family member who is aware of their HIV status, and be aware of the benefits of CPT. The majority of participants who complied with CPT were more likely to have experienced counseling during refill, felt that the length of time spent seeing doctors for treatment was reasonable, and received accurate information from them. Conclusion: Most adult HIV patients attending CTC at BMC were reported to be in compliance with CPT. These findings suggest that improving social support and patient-provider communication may be effective strategies for improving compliance with CPT among HIV patients.

Total hip arthroplasty for sequelae of childhood hip disorders:Current review of management to achieve hip centre restoration

Adults requiring total hip arthroplasty(THA)for childhood disorder sequelae present with shortening,limp,pain,and altered gait.THA,which can be particularly challenging due to altered anatomy,requires careful planning,assessment,and computed tomography evaluation.Preoperative templating is essential to establish the appropriate acetabular and femoral size.Information regarding neck length and offset is needed to ensure the proper options are available at THA.Hip centre restoration must be planned preoperatively and achieved intraoperatively with appropriate exposure,identification,and stable fixation with optimum-size components.Identifying the actual acetabular floor is essential as changes include altered anatomy,distortion of the margins and version changes.Proximal femur changes include anatomical variation,decreased canal diameter,cortical thickness,changes in anteversion,and metaphyseal and diaphyseal mismatch.Preoperative assessment should consist of limb assessment for variations due to prior surgical procedures.Evaluation of the shortening pattern with the relationship of the lesser trochanter to the teardrop would help identify and plan for subtrochanteric shortening osteotomy,especially in high-riding hips.The surgical approach must ensure adequate exposure and soft tissue release to achieve restoration of the anatomical hip centre.The femoral components may require modularity to enable restoration of anteversion and optimum fixation.

加拿大多伦多Sunnybrook Health Sciences Centre NICU护理对我国的借鉴

通过介绍Sunnybrook Health Sciences Centre NICU的护理管理和工作制度、医院感染预防、病房布局、护理业务培训和对早产儿发育的护理等内容,为我国NICU护理工作开展提供借鉴。提出我国应该加强根据国内外的最新护理进展情况规范NICU护士专科知识教材和培训方法;合理布局NICU,以改善病房环境和预防医院感染;合理安排治疗和护理时间,尽量减少对早产儿的干扰,促进其发育;鼓励父母参与患儿的护理。

Application of face centred cubic TiB powder as conductive filler for electrically conductive adhesives

Face centred cubic（FCC） TiB ceramic powder synthesized by Ti-boronizing method was used as conductive filler to make ceramic electrically conductive adhesives（ECAs） with the polymer matrix.Electrically conductive properties of the ceramic ECAs were studied.The bulk electrical resistivity varied with the powder content of the FCC-TiB in ECAs.The FCC-TiB filled ECAs also showed the percolation behavior that usually occurred for the metal-filled ECAs,the percolation threshold was located at the content of 60%FCC-TiB.A minimum value of 0.1 Ω·cm was obtained at a content of 75%FCC-TiB.In order to check the reliability of mechanical property,tensile test was done to measure the shear strength,and the shear strength dropped with increasing the content of FCC-TiB powders.It is about 12.26 MPa at the content of 70%TiB powders.The Cu filled ECAs were also prepared for comparison.The properties of the oxidation resistance of the two ECAs were evaluated.The results show that the ceramic ECAs have excellent oxidation resistance and better stability compared with the Cu filled ECAs.

菲律宾St. Luke's Medical Centre NICU学习感悟

本文通过介绍菲律宾St.Luke's Medical Centre NICU的护理工作制度、服务理念、培训制度以及病房布局、母乳喂养的落实情况、对早产儿的发展性照顾等方面的情况,旨在为我国规范NICU护士专科知识的培训、优化病房环境、加强发展性护理、鼓励父母参与患儿的护理、加强患儿出院前的指导、提高NICU护理工作水平提供参考。

A 162GHz Self-Aligned InP/InGaAs Heterojunction Bipolar Transistor

An emitter self-aligned InP-based single heterojunction bipolar transistor with a cutoff frequency （fT） of 162GHz is reported. The emitter size is 0.8μm × 12μm, the maximum DC gain is 120, the offset voltage is 0.10V,and the typical breakdown voltage at Ic = 0. 1μA is 3.8V. This device is suitable for high-speed low-power applications,such as OEIC receivers and analog-to-digital converters.

The influence of trapping centres on the photoelectron decay in silver halide

Photoelectron is the foundation of latent image formation, the decay process of photoelectrons is influenced by all kinds of trapping centres in silver halide. By analysing the mechanism of latent image formation it is found that electron trap, hole trap, and one kind of recombination centre where free electron and trapped hole recombine are the main trapping centres in silver halide. Different trapping centres have different influences on the photoelectron behaviour. The effects of all kinds of typical trapping centres on the decay of photoelectrons are systematically investigated by solving the photoelectron decay kinetic equations. The results are in agreement with those obtained in the microwave absorption dielectric spectrum experiment.

Colour Centres and Energy Transfer in BaF_(2-x)Cl_x∶Eu^(2+) Phosphors

The optical absorption spectra of BaF2-x Clx ：Eu^2＋ after ultraviolet （UV） light excitation were investigated. The differences between the absorption spectra after and before excitation （DAS） were observed. The DAS increase at both the high and the low energy side of F band in BaF2-xClx ： Eu^2 ＋ after 245 nm UV light excitation. The bleach effect of UV light and the absorption of electrons in the valence band may account for the former and the formation of Fa centres （association of F（Cl^-） centres）, whose absorption band matches the HeNe laser better, may explain the latter. In the write-in process, the transfer of electrons is via tunneling, In the readout process, the transfer of electrons captured in F（F^-） and Fa centres is more likely via tunneling, and that of F（Cl^- ） centres is more likely via conduction band.

Performance of a Self-Aligned InP/GaInAs SHBT with a Novel T-Shaped Emitter

A self-aligned InP/GalnAs single heterojunction bipolar transistor（HBT） is investigated using a novel T-shaped emitter. A U-shaped emitter layout,selective wet etching,laterally etched undercut, and an air-bridge are applied in this process. The device, which has a 2μm×12μm U-shaped emitter area,demonstrates a common-emitter DC current gain of 170,an offset voltage of 0.2V,a knee voltage of 0.5V, and an open-base breakdown voltage of over 2V. The HBT exhibits good microwave performance with a current gain cutoff frequency of 85GHz and a maximum oscillation frequency of 72GHz, These results indicate that these InP/InGaAs SHBTs are suitable for low-voltage,low-power,and high-frequency applications.

Nonlinear consensus protocols for multi-agent systems based on centre manifold reduction

Nonlinear consensus protocols for dynamic directed networks of multi-agent systems with fixed and switching topologies are investigated separately in this paper. Based on the centre manifold reduction technique, nonlinear consensus protocols are presented. We prove that a group of agents can reach a β-consensus, the value of which is the group decision value varying from the minimum and the maximum values of the initial states of the agents. Moreover, we derive the conditions to guarantee that all the agents reach a β-consensus on a desired group decision value. Finally, a simulation study concerning the vertical alignment manoeuvere of a team of unmanned air vehicles is performed. Simulation results show that the nonlinear consensus protocols proposed are more effective than the linear protocols for the formation control of the agents and they are an improvement over existing protocols.

Scalable fabrication of geometry-tunable self-aligned superlattice photonic crystals for spectrum-programmable light trapping

Superlattice photonic crystals (SPhCs) possess considerablepotentials as building blocks for constructing high-performancedevices because of their great flexibilities in opticalmanipulation. From the prospective of practical applications,scalable fabrication of SPhCs with large-area uniformity and precisegeometrical controllability has been considered as one prerequisitebut still remains a challenge.

Mechanism of fracture in macro- and micro-scales in hollow centre cracked disc specimen

The hollow centre cracked disc(HCCD) specimen is one of the suggested alternative methods for determining the fracture toughness of rock. This work aims to investigate the fracture mechanism in HCCD in macro- and micro-scales using numerical methods, extended finite element method(X-FEM) and particle flow code(PFC) modeling, respectively. In the X-FEM, heaviside and near-tip enrichment functions are employed to consider the presence of the crack in the model. In PFC modeling the movement and interaction of stressed assemblies of rigid spherical particles are modeled using the distinct element method(DEM). A numerical code called MEX-FEM based on XFEM has been developed to simulate the problems involving crack. The models of pure modes I and Ⅱ in macro-scale are simulated in micro-scale. The results show that dimensionless stress intensity factors(YI, YⅡ) for pure modes I and Ⅱ increase by increasing the crack length ratio. The angle at which the pure mode Ⅱ occurs decreases by increasing the crack length ratio. In mixed mode I-Ⅱ, The value of YI decreases by increasing the crack angle, while the value of YⅡ increases to a given crack angle and then it decreases. Moreover, the fracture in micro-scale, unlike the macro-scale, includes a combination of different modes of fracturing.

Clinical characteristics and in-hospital outcomes of patients receiving contemporary intensive cardiac care:retrospective study from a large centre in China

BACKGROUND Few studies from developed countries have quantitatively characterized the clinical characteristics and outcomes of patients receiving contemporary intensive cardiac care.We sought to investigate these data in patients admitted to a Chinese intensive cardiac care unit(ICCU).METHODS We conducted a retrospective study using data from 2,337 consecutive admissions to the ICCU at a large centre in China from June 2016 to May 2017.Data were captured after systematic inspection of individual medical records regarding current demographics,primary diagnosis,comorbidities,illnesses severity,and in-hospital outcomes.RESULTS The mean age was 65.6±14.2 years,and females accounted for 32.0%of patients.The Charlson Comorbidity Index and Oxford Acute Severity of Illness Score were 2.4±1.8 and 22.5±10.4,respectively.The top reason for admission was ST-segment elevation myocardial infarction(32.0%),and nonischaemic heart diseases accounted for 31.2%of all primary diagnoses.Noncardiovascular diseases were prevalent in the ICCU population,including chronic illnesses and acute noncardiovascular critical illnesses(ANCIs);in particular,21.7%of patients were marked by acute respiratory failure(14.6%),acute kidney injury(13.7%),sepsis(4.2%),or gastrointestinal bleeding(3.3%).The median length of stay in the ICCU and hospital were 1.1 days[interquartile range(IQR):0.8–2.6 days]and 6.3 days(IQR:3.8−10.9 days),respectively.The overall incidence of in-hospital death or discharge against medical advice under extremely critical conditions was 7.6%(n=177).Multivariate logistic regression analysis showed that the complexity of chronic illnesses and incident ANCIs were strong independent determinants for in-hospital outcomes.CONCLUSIONS Remarkable patient diversity and breadth of critical illnesses were observed in a Chinese ICCU population.Particularly,noncardiovascular diseases were prevalent and associated with adverse outcomes.Reformation of organization and staffing practices may be considered to adapt to the changed landscape.

Self-alignment of full skewed RSINS: observability analysis and full-observable Kalman filter

Traditional orthogonal strapdown inertial navigation sys-tem （SINS） cannot achieve satisfactory self-alignment accuracy in the stationary base： taking more than 5 minutes and al the iner-tial sensors biases cannot get ful observability except the up-axis accelerometer. However, the ful skewed redundant SINS （RSINS） can not only enhance the reliability of the system, but also improve the accuracy of the system, such as the initial alignment. Firstly, the observability of the system state includes attitude errors and al the inertial sensors biases are analyzed with the global perspective method： any three gyroscopes and three accelerometers can be assembled into an independent subordinate SINS （sub-SINS）;the system state can be uniquely confirmed by the coupling connec-tions of al the sub-SINSs;the attitude errors and random constant biases of al the inertial sensors are observable. However, the ran-dom noises of the inertial sensors are not taken into account in the above analyzing process. Secondly, the ful-observable Kalman filter which can be applied to the actual RSINS containing random noises is established; the system state includes the position, ve-locity, attitude errors of al the sub-SINSs and the random constant biases of the redundant inertial sensors. At last, the initial self-alignment process of a typical four-redundancy ful skewed RSINS is simulated： the horizontal attitudes （pitch, rol ） errors and yaw error can be exactly evaluated within 80 s and 100 s respectively, while the random constant biases of gyroscopes and accelero-meters can be precisely evaluated within 120 s. For the ful skewed RSINS, the self-alignment accuracy is greatly improved, mean-while the self-alignment time is widely shortened.

Fabrication and characterization of groove-gate MOSFETs based on a self-aligned CMOS process

N and P-channel groove-gate MOSFETs based on a self-aligned CMOS process have been fabricated and characterized. For the devices with channel length of 140nm, the measured drain induced barrier lowering （DIBL） was 66mV/V for n-MOSFETs and 82mV/V for p-MOSFETs. The substrate current of a groove-gate n-MOSFET was 150 times less than that of a conventional planar n-MOSFET, These results demonstrate that groove-gate MOSFETs have excellent capabilities in suppressing short-channel effects. It is worth emphasizing that our groove-gate MOSFET devices are fabricated by using a simple process flow, with the potential of fabricating devices in the sub-100nm range.

Energy-Aware Scheduling Scheme Using Workload-Aware Consolidation Technique in Cloud Data Centres

To reduce energy consumption in cloud data centres,in this paper,we propose two algorithms called the Energy-aware Scheduling algorithm using Workload-aware Consolidation Technique(ESWCT) and the Energyaware Live Migration algorithm using Workload-aware Consolidation Technique(ELMWCT).As opposed to traditional energy-aware scheduling algorithms,which often focus on only one-dimensional resource,the two algorithms are based on the fact that multiple resources(such as CPU,memory and network bandwidth)are shared by users concurrently in cloud data centres and heterogeneous workloads have different resource consumption characteristics.Both algorithms investigate the problem of consolidating heterogeneous workloads.They try to execute all Virtual Machines(VMs) with the minimum amount of Physical Machines(PMs),and then power off unused physical servers to reduce power consumption.Simulation results show that both algorithms efficiently utilise the resources in cloud data centres,and the multidimensional resources have good balanced utilizations,which demonstrate their promising energy saving capability.