一种轧辊轴承座辅助装配装置的设计研究

设计了一种新型的轧辊轴承座辅助装配装置,该装置是一种对轧辊轴承座与轧辊进行安装和拆卸的辅助工装,结构简单,易于操作。另外还介绍了对装置的核心部件进行设计计算及强度校核的方法,并对该装置进行了Inventor三维建模,从而更加形象、直观地展示其工作原理。     

机油泵转子轴上销孔的钻床夹具设计

从机油泵转子的基本结构出发,给出了转子轴上钻孔夹具的定位、夹紧方案,定位、夹紧装置的设计及专用钻模的总体结构设计,并针对专用钻模通用性不足的问题,提出了可调夹具、组合夹具等多种解决方案,在保证钻孔质量的同时,提高加工效率,减少加工准备时间,降低生产成本。     

电解槽罩板装卸装置的设计研究

电解槽罩板装卸装置是安装在铝电解多功能起重机上的辅助生产装置.文中阐述了该装置设计研究的重要性,介绍了国内外的研究现状及目前槽罩板的结构形状.文中以一种结构的槽罩板为基础,并综合考虑其他槽罩板的形状进行了设计研究,介绍了该装置的设计方案,详细地说明了该装置的布置形式及结构组成,并对各组成部分的功能及特点进行了分析论述....     

阳极炭块夹具的最佳设计值

从最佳设计角度出发,给出了炭块堆垛天车夹具横梁上的滑轮安装之最佳位置,并找出夹具杆件的最佳几何布局,从而使夹具组刚性大,变形小,夹具的夹紧力充分作用在炭块上,并保证夹持熟阳极炭块的夹紧力大于夹持生阳极炭块的夹紧力。据以设计的天车不仅降低了整机重量,提高了天车的可靠性和寿命,同时保证了炭块在堆垛时不被破坏。     

A new device for fretting fatigue testing

Fretting fatigue damage occurs in contacting parts when they are subjected to fluctuating loads and sliding movements at the same time. Fretting fatigue can reduce the fatigue life of materials by half or even more. Fretting fatigue tests are usually performed using universal hydraulic testing devices. The contact pressure is produced by a fixture, typically designed and manufactured by researchers. In this investigation, a new device is introduced in which the fluctuating loading is supplied by a variable crank system (VCSD). The device called VCSD for abbreviation is basically a position control machine in which displacements can be imposed with an accuracy of 0.01 mm. The axial and contact loads are measured by load cells. The friction load is also measured by using foil strain gauges using a Wheatstone bridge configuration. The functionality of the device is examined by making a comparison between fretting fatigue lives of a number of Al7075-T6 specimens tested on a universal testing machine and VCSD. The results show a very close agreement between the functionality of the two testing rigs. The main advantages of VCSD are its higher frequency with respect to universal devices, simplicity, and cheapness. It can be developed further for high and low temperature tests in future.     

A working cardiac valve phantom for radiographic assessment of prosthetic heart valves

RATIONALE AND OBJECTIVES: A working valve phantom (WVP) that both exercises the valve occluder and simulates movements of the mitral annulus is described. It was designed to develop a method for radiographic detection of a single broken leg of the two-legged Bj?rk-Shiley convexo-concave (C/C) heart valve outlet strut. METHODS: The WVP consists of a pneumatically driven left ventricular assist device immersed in 22 cm of water. Left ventricular assist device annulus movements are generated by systolic turgor and diastolic relaxation of the aortic outflow graft within limits set by the holding fixture design. RESULTS: WVP images were comparable in attenuation, valve motion, and diagnostic sensitivity to clinical C/C valve images and were effective in assessing leaflet excursions in another valve model. Techniques developed in the WVP have proved successful in the clinical detection of C/C valves that have a single broken leg but that show normal function in all other tests. CONCLUSION: The WVP can be a useful tool for developing refined radiographic assessments of prosthetic heart valves.     

In vitro studies on the effect of cleaning methods on different implant surfaces

The effect of specific cleaning procedures was examined on the surfaces of 3 implant types with different coatings and shapes (plasma sprayed [PS]; hydroxyapatite coated [HA] implants; and smooth titanium surface screws) using a scanning electron microscope. Each implant was treated for 60 seconds per instrument with one of 6 different hygiene measures: plastic curet, metal curet, diamond polishing device, ultrasonic scaler, air-powder-water spray with sodium hydrocarbonate solution, and chlorhexidine 0.1% solution rinse. The air-powder-abrasive system, chlorhexidine rinse, and curettage with a plastic instrument caused little or no surface damage in all but the hydroxyapatite-coated fixtures. Therefore, these 3 methods were tested to determine their cleaning efficacy in a second clinical study, which did not include the HA-coated fixture. Two implants were placed on the facial aspects of both upper molar regions using individual acrylic plates. Thus, 2 fixtures on each side were examined in each patient. The examination revealed that only the sodium hydrocarbonate spray yielded a clean fixture without damage to the implant surface. In a third stage, which imitated the clinical procedure of the second approach, the cell growth of mouse-fibroblasts on implant surfaces was examined after cleaning the surface with plastic scaler and the air-abrasive system, which represents the least damaging and most effective methods. In contrast to the implant surfaces treated with plastic scalers, mostly vital cells were found on implants sprayed with the air-abrasive system.     

优化夹具设计提高薄壁铝筒加工质量

薄壁铝筒零件由于壁薄、刚性差,加工中容易出现变形、振刀现象,加工质量难以保证。本文通过对零件夹具进行优化设计,满足了零件设计要求,为薄壁类零件的加工提供了一种可靠方法。     

Review of Handbook of the psychology of aging, 7th edition.

Reviews the book, Handbook of the psychology of aging, 7th edition edited by K. Warner Schaie and Sherry L. Willis (see record 2010-26788-000). The Handbook of the psychology of aging has been a fixture since its inception in 1977. Although the departure of former senior editor James E. Birren has given rise to a “generational turnover” (p. xi), the new volume keeps alive the interdisciplinary spirit of the series by continuing to combine cutting-edge basic and applied perspectives from a diverse set of contributors. Section editors and authors include senior figures in the field who have contributed to prior volumes of the Handbook, as well as new scientific leaders who may not yet be “household names.” The volume is organized into four sections: theory and methods, neuroscience and cognition, social and health factors, and psychopathology. Each section contains 3–8 chapters of varying structure and length. With the exception of the first section, each section includes topics that were not included, or received significantly less coverage, in prior editions. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

车床改装拉床的设备改造技术

介绍了将普通车床改装为拉床的技术方法。在车床上增加了一套夹具装置 ,可将车床的回转运动改为直线往复运动 ,车床主轴可只输出扭矩 ,而由夹具装置承受拉削力 ,从而实现由车床向拉床的改造。该方法简单 ,制造容易 ,能满足质量要求 ,且改装费用低廉     

Molecular basis for cardiac functions

The cause of mechanical failure of the fixture component of an osseointegrated dental implant was investigated. The surfaces of five clinical specimens that had fractured were compared to those of new specimens fractured in the laboratory under monotonic and cyclic loads. Scanning electron microscopy revealed striations on the fractured surfaces of the clinical specimens, similar to striations on the laboratory-fatigued specimens and in contrast to the dimpled surfaces on the overloaded specimens. The investigation demonstrated that fractures of the fixture component of this dental implant occurred by fatigue under physiologic loads, with marginal alveolar bone loss around the fixture.     

火花放电原子发射光谱多功能光谱夹具的研究与应用

为了解决了目前光谱夹具的单一性问题,研究并开发了多功能光谱夹具,并将其用于火花放电原子发射光谱分析中。多功能光谱夹具是融合了传统的立式和卧式夹具的原理改进而成,通过合理的拆卸设计,完成棒、线、管、片材和球状样品的分析测试。根据卧式光谱夹具的原理,可用于外径或宽度在1.0~10mm之间棒、线、管、片材样品分析;另外该夹具根据立式光谱夹具的原理,将圆球形样品借助不锈钢钢管、弹簧及螺栓完成了向棒材样品转换,通过定位板和V型板的定位,可用于外径在2.5~10mm之间钢球样品的测定。     

堆垛机组新型自适应夹具的研制

针对电解铝厂所用碳块规格多样化特点,分析原堆垛机组中使用的自重式夹具在结构上存在的问题,研制出新型自适应夹具.文章介绍了堆垛机组自适应夹具的结构特点及其市场应用前景.     

The Orthosystem--a new implant system for orthodontic anchorage in the palate

The present report describes the design and first clinical experiences of a newly developed endosseous orthodontic implant anchor system (Orthosystem, Institut Straumann, Waldenburg, Switzerland) for palatal anchorage. The 1-piece fixture made of titanium consists of a screw-type endosseous implant body (sandblasted, acid-etched, diameter 3.3 mm, lengths: 4 and 6 mm), a cylindrical polished transmucosal neck and an abutment. Clamp-caps provide attachment of square commercially available orthodontic wires (0.032 x 0.032 inch, SS) to the abutment (transpalatal bars). In a pilot study 1 fixture (implant body length: 6 mm) was inserted into the midsagittal anterior palatal region in each of 6 adult patients with Angle class II malocclusion (distocclusion 7 to 8 mm, overjet: approximately 9 mm). The treatment plan included extraction of the first maxillary premolars and retraction of the anterior teeth based on maximum anchorage of the posterior teeth without using compliance-dependent anchorage aids (headgear, class II elastics). Due to the design of the fixture only 1 simple surgical procedure was required for insertion (nonsubmerged method, 1-stage surgery). Accordingly the need for surgical exposure of the abutment for connection and wire insertion was eliminated. Thus, inconvenience to patients was reduced to a minimum. The patients are now at varying active treatment stages. The course of treatment of the most advanced case is described. Evaluation of the clinical and radiological findings after 12 months of treatment (3 months implant healing, 9 months active orthodontic treatment which is equal to the implant loading period) revealed no implant mobility/dislocation, favourable peri-implant soft tissue conditions, no marked mesial movement (approximately 0.5 mm) of the implant/transpalatal bar supported posterior teeth, and 8 mm retraction of the anterior teeth. Retrieval of the fixture and post-operative wound healing were uncomplicated. In the treatment of this case, no compliance-dependent extraoral anchorage was used, and the well aligned mandibular dentition was not bonded provide anchorage support (class II elastics).     

Factors associated with elevated rates of adverse outcomes after cyclodestructive procedures versus drainage device procedures

OBJECTIVE: To identify factors associated with an increased risk of adverse outcomes after cyclodestructive or drainage device procedures. DESIGN: Retrospective, cohort analysis. PARTICIPANTS: A total of 5570 Medicare patients who were older than 65 years of age and who underwent cyclodestructive or drainage device procedures in 1994 participated. INTERVENTION: The authors identified cyclodestructive and drainage device procedures from claims to the Health Care Finance Administration (HCFA) by International Classification of Diseases (ICD-9) procedure codes, Current Procedural Terminology procedure codes, and HCFA Common Procedural Classification System codes. The authors analyzed adverse outcome rates using hierarchical logistic regression. Race, age group, gender, length of observed follow-up, state in which surgery took place, ocular procedures performed before and at the same time as the index surgery, and ocular diagnosis were included as covariates in the model. MAIN OUTCOME MEASURES: The authors defined an adverse outcome as the occurrence after the index surgery of at least one of the following: repeat cyclodestructive or drainage device procedure, retinal hole-tear repair, retinal detachment repair, surgery for endophthalmitis, vitrectomy, enucleation, evisceration, surgery for ocular hypotony, and/or extrusion or revision of drainage device. Adverse outcomes were also defined without the inclusion of repeat cyclodestructive or drainage device procedures. RESULTS: When repeat cyclodestructive or drainage device procedures were not included in the definition of an adverse outcome, eyes with a drainage device procedure were 3.8 times more likely to have an adverse outcome than eyes with a cyclodestructive procedure (odds ratio [OR], 3.8; 95% confidence interval [CI], 3.07, 4.67). Subjects with concurrent corneal transplant had increased odds of an adverse outcome compared to subjects without a concurrent corneal transplant (OR, 2.00; 95% CI, 1.27, 3.15). When the definition of an adverse outcome included repeat cyclodestructive or drainage device procedures, the odds of an adverse outcome were similar for both cyclodestructive and drainage device procedures (OR, 0.94; 95% CI, 0.79, 1.13). CONCLUSIONS: Cyclodestructive procedures need to be repeated more frequently than drainage device procedures. However, if the patient has a drainage device procedure, then that patient is more likely to have other types of adverse ophthalmic events than if he or she had a cyclodestructive procedure. Because the average follow-up of subjects in this study is 5 months (range, 0-12 months), outcomes that might take longer to manifest themselves would be excluded from this study.     

A simple means for accurate breast volume determination

The authors have developed a simple, accurate, and inexpensive device for measuring the volume of the female breast. The concept is based on an adjustable geometrical conical form into which the breast is placed. The breast volume is then easily read from a graduated scale on the device. The device is available in sterile prepackaged form for intraoperative use. The various applications and advantages are described.     

New automatic test for the study of platelet response to variations in osmotic pressure: application in the evaluation of the viability of platelet concentrates

Studying the osmotic resistance or swelling of platelets has often been suggested as a global test to assess the viability of those cells. A number of authors have also analysed the behaviour of platelets in hypotonic media by a variety of complementary methods (cell count, morphology, determinations of substances released, photometric measurement of aggregation induced by aggregating agents, etc). Most studies are currently based on the so-called "osmotic shock response" test, which measures according to time the light transmitted through platelet-rich plasma (PRP) after dilution in distilled water. In this study, the authors describe a new automated and reproducible test using slow dialysis to assess platelet osmotic resistance. The "Fragilimeter", a device initially described by the authors to characterise RBC fragility, has been adapted to the study of platelet osmotic behaviour. The variations in light transmission through a platelet suspension according to NaCl concentration are linked to the change in cellular volume and lysis and characterise the viability of the cells. The results obtained with normal platelets revealed the good reproducibility of the technique. The osmotic resistance is evaluated for two parameters: anticoagulant (citrate, EDTA) and cellular concentration. The test was applied to quality control of stored platelet concentrates for transfusion, prepared with different cell separators.     

Using the shape recovery of nitinol in the Harrington rod treatment of scoliosis

Nitinol, a metal alloy which is able to remember (and return to with slight heating) the shape it had before it was deformed, is demonstrated to be useful in the Harrington rod treatment of scoliosis. A bent nitinol rod can return to its original straight length, applying both axial and lateral forces to the spine during the operation of postoperatively by means of external heating. A research program using simulated spinal forces in a test fixture and implantation in a cadaver was undertaken to show the feasibility of modifying the existing procedure.     

Sildenafil (Viagra) for treating male erectile dysfunction

Many procedures performed by podiatric surgeons today require the use of a soft-tissue anchoring device. In recent years, many new anchoring devices have become available for use in the foot and ankle. The authors introduce a new soft-tissue anchoring device that has yet to be described in the podiatric literature and present two cases in which the new anchor was used.     

Follow-up of fibrin clot growth in blood plasma

The authors propose a device for following up the kinetics of the fibrin clot enlargement in the plasma. Coagulation is induced by contact activation with a fragment of an arterial wall put into the plasma. Besides the initial time of clot formation, the device helps assess the rate of clot growth. Two phases of contact-induced clotting may be distinguished. The first is slow activation of the clotting system and formation of minor amounts of fibrin, the other is rapid growth of the clot, with the linear increment of the clot size being constant during 15 min.