面向对象图形数据库技术的实现

结合实例介绍了一种基于图形的面向对象数据库管理系统ＯＯＤＢＭＳ的设计。同时介绍了ＯＯＤＭＢＳ的结构和功能以及用ＤＥＬＰＨＩ语言进行实现。     

SBS与MMA本体接枝物的合成与表征

以过氧化苯甲酰（ＢＦＯ）作引发剂，用甲基丙烯酸甲酯（ＭＭＡ）既作为热塑性弹性体（ＳＢＳ）的溶剂又作为与ＳＢＳ进行接枝共聚反应的单体，合成得到了接枝共聚物ＳＢＳ－ｇ－ＭＭＡ；用红外光谱、核磁共振谱、透射电镜、扫描电镜及动态粘弹谱对其组成和结构进行了表征。     

橡胶增韧AS树脂研究

用ＮＢＲ、ＥＶＡ、ＭＢＳ和ＣＰＥ单独或联合增韧ＡＳ树脂，研究表明，ＭＢＳ／ＮＢＲ和ＭＢＳ／ＣＰＥ对ＡＳ树脂有协同增韧效应，ＥＶＡ可作为ＡＳ／ＮＢＲ体系的相容剂，ＮＢＲ中ＡＮ含量将影响增韧效果，并用ＴＥＭ和ＳＥＭ观察了共混物的形态。     

PPO/SEBS-g-MAH共混体系的冲击断面和微观形变过程

用扫描电子显微镜（ＳＥＭ）观察了ＰＰＯ／ＳＥＢＳ和ＰＰＯ／ＳＥＢＳ－ｇ－ＭＡＨ共混物的常温缺口冲击断面,发现ＰＰＯ／ＳＥＢＳ共混体系的冲击断布有大量韧窝;ＰＰＯ／ＳＥＢＳ－ｇ－ＭＡＨ共混体系由呈现中心为棒,四周为环的冲击断面形貌,对ＰＰＯ／ＳＥＢＳ－ｇ－ＭＡＨ冲击断的应力发白区的ＳＥＭ观察结果表明在冲击断面下方,合金发生大的取向;ＴＥＭ的观察结果显示在应力发白区内,弹性体周围存在大量的微穴,未发现     

MJS快速成型制备金属多孔材料

介绍了一种新的快速成型技术－多相喷射沉积（ＭＪＳ），分析讨论了ＭＪＳ快速成型系统的设计，原型零件的成型工艺过程，制定了后处理工艺，最后给出了用ＭＪＳ制备Ｎｉ６０金属多孔材料的显微组织和性能。     

机械制造企业怎样选择数据库管理系统DBMS

根据济南二机床集团公司应用计算机建立信息管理系统十多年的经验，指出关系型ＤＭＢＳ系统必须有类似ＳＱＬ的第四代主同级语言来支持，ＯＲＡＣＬＥＲＤＢＭＳ是标准的关系型ＤＭＢＳ的数据操纵语言。介绍了济南二机床集团应用ＯＲＣＡＬＥＲＤＢＭＳ的实例。     

积木式建模系统的研究

积木式建模系统（ＢＭＢＳ）是构造模型库管理系统的一种先进方法，它可以给用户提供一个模型库的原型系统，用户根据自己的需求，建造面向特定对象的模型库。由于ＢＭＢＳ必须以集成知识环境为支撑，所以它实际上又可以成为开发ＤＳＳ的原型系统。本文介绍了我们开发的ＢＭＢＳ。     

用IBM－PC计算机测试SSPA器件参数的数据采集系统

介绍用ＩＢＭ－ＰＣ计算机辅助测试ＳＳＰＡ器件参数的１２位高速数据采集系统。该系统带有缓冲ＲＡＭ，对ＳＳＰＡ的视频信号采集速度可达５００ｋＨｚ，适合于各种需要对ＳＳＰＡ器件进行高速高精度采集的应用。     

用IBM—PC计算机测试SSPA器件参数的数据采集系统

介绍用ＩＢＭ－ＰＣ计算机辅助测试ＳＳＰＡ器件参数的１２位高速数据采集系统。该系统带有缓冲ＲＡＭ，对ＳＳＰＡ的视频信号采集速度可达５００ｋＨｚ，适合于各种需要对ＳＳＰＡ器件进行高速高精度采集的应用。     

几种材料的微生物腐蚀

用扫描电镜、电子探针等,研究了不锈钢、Ｑ２３０钢、工业纯铝、工业黄铜等材料对硫酸盐还原菌（ＳＲＢ）的腐蚀敏感性,结果表明Ｑ２３０钢易生长生物膜,其主要腐蚀产物为ＦｅＳ,以点蚀为主。不锈钢、工业纯铝等材料若有缺陷及残余应力处、有利于细菌生长,黄铜耐ＳＲＢ腐蚀。化学镀Ｎｉ－Ｐ和Ｎｉ－Ｍｏ－Ｐ可提高Ｑ２３０钢耐微生物腐蚀能力。     

Characterization and three-dimensional reconstruction of synthetic bone model foams

Sawbones© open-cell foams with different porosity grades are being used as synthetic bone-like models for in vitro mechanical and infiltration experiments. However, a comprehensive characterization of these foams is not available and there is a lack of reliable information about them. For this reason two of these foams (Refs. 1522-505 and -507) have been characterized at the micro architectural level by scanning electron microscopy, computed tomography and image data analysis. BoneJ open software and ImageJ open software were used to obtain the characteristic histomorphometric parameters and the three dimensional virtual models of the foams. The results showed that both foams, while having different macro porosities, appeared undistinguishable at the micro scale. Moreover, the micro structural features resembled those of osteoporotic rather than healthy trabecular bone. It is concluded that Sawbones© foams behave reasonably as synthetic bone-like models. Consequently, their use is recommended for in vitro comparison purposes of both mechanical and infiltration testing performed in real vertebra. Finally, the virtual models obtained, which are available under request, can favour comparisons between future self-similar in vitro experiments and computer simulations.     

Characterization of polymeric structural foams under compressive impact loading by means of energy-absorption diagram

The mechanical properties at room temperature of three polymeric foams (namely EPP, PUR and PS/PA foams) have been experimentally evaluated in both static and impact loading conditions. The energy absorption characteristics have been examined both through the energy-absorption diagram method and through the efficiency diagram method. The meaning of the efficiency parameter, already used in the literature, has been explained in a proper, satisfactory way. It is shown that the maximum of the efficiency identifies the condition for optimal energy absorption of the foam, while the maximum stress reaches a value limited through other design considerations. The efficiency diagram method is then used to obtain synthetic diagrams useful to characterize the material and to help the design of energy absorbing components. These synthetic selection diagrams are obtained for the three tested materials. Finally, some consideration are drawn comparing the mechanical performance of the three considered types of foams and their dependency on density.     

Evaluation of a biodegradable foam for protective packaging applications

Green Cell^® foam (GCF) is a biodegradable foam packaging material produced from a proprietary cornstarch blend. It is commercially available in a variety of laminations and constructions. Cushioning ability and thermal resistance (R‐value) are the fundamental properties needed to compete against synthetic foams. Since GCF is starch based and biodegradable, a concern was that moisture would likely affect its physical properties. Cushioning characteristics and insulation R‐values of 1 and 2 inch foams were determined as a function of temperature and moisture content. The ASTM method D1596 was used to determine the cushioning properties and an ice melt test was used to determine the thermal resistance. Moisture sorption isotherms were developed at three temperatures (20, 25 and 30°C) to determine its moisture sensitivity. The 1‐inch‐thick foam had lower G values at lower static stresses than synthetic foams, but had higher G values at higher static stresses. The 2‐inch‐foam had G values similar to that of synthetic foam materials. Dimensional changes were observed at higher relative humidity (RH) conditions, especially at 30°C. The R‐values at higher humidities were also less than that of synthetic materials. Copyright © 2007 John Wiley & Sons, Ltd.     

中间相沥青基泡沫炭的气泡生长过程

以AR合成中间相沥青为原料,在不同的温度下发泡制得了泡沫炭.采用扫描电镜和光学显微镜等分析手段对中间相沥青基泡沫炭的气泡生长机理进行了初步研究,讨论了温度对泡孔结构的影响.结果表明,当温度从480℃升至540℃时,平均泡孔直径从500μm升到800μm.最初形成的泡沫在熔融沥青中分布不均匀,汇集在沥青的上表面;气泡在Z轴方向的形状是椭球形,在Z轴垂直方向为球形.中间相沥青基泡沫炭气孔的形状和泡沫的体积密度密切相关.形成的泡沫体在z轴方向存在明显的体积密度梯度.     

Comparison of a low molecular weight and a macromolecular surfactant as foaming agents for injectable self setting hydroxyapatite foams: Polysorbate 80 versus gelatine

Hydroxyapatite foams are potential synthetic bone grafting materials or scaffolds for bone tissue engineering. A novel method to obtain injectable hydroxyapatite foams consists in foaming the liquid phase of a calcium phosphate cement. In this process, the cement powder is incorporated into a liquid foam, which acts as a template for macroporosity. After setting, the cement hardens maintaining the macroporous structure of the foam. In this study a low molecular weight surfactant, Polysorbate 80, and a protein, gelatine, were compared as foaming agents of a calcium phosphate cement. The foamability of Polysorbate 80 was greater than that of gelatine, resulting in higher macroporosity in the set hydroxyapatite foam and higher macropore interconnectivity. Gelatine produced less interconnected foams, especially at high concentrations, due to a higher liquid foam stability. However it increased the injectability and cohesion of the foamed paste, and enhanced osteoblastic-like cell adhesion, all of them important properties for bone grafting materials.     

深海高强浮力材料的研究现状

深海开发迫切需要高强轻质浮力材料。概述了深海浮力材料的国内外研究现状、固体浮力材料的类别及应用;结合新型高强浮力材料的开发,具体介绍了以环氧树脂为基体、填充空心玻璃微珠的轻质浮力材料的研究历程、制备工艺及常见理化性能的测试方法,分析了今后重点研究的方向。     

Mechanical properties of open-cell foam synthetic thoracic vertebrae

This study presents comprehensive morphological and mechanical properties (static, dynamic) of open-cell rigid foams (Pacific Research Laboratories Inc. Vashon, WA) and a synthetic vertebral body derived from each of the foams. Synthetic vertebrae were comprised of a cylindrical open-cell foam core enclosed by a fiberglass resin cortex. The open-cell rigid foam was shown to have similar morphology and porosity as human vertebral cancellous bone, and exhibited a crush or fracture consolidation band typical of open-celled materials and cancellous bone. However, the foam material density was 40% lower than natural cancellous bone resulting in a lower compressive apparent strength and apparent modulus in comparison to human bone. During cyclic, mean compression fatigue tests, the synthetic vertebrae exhibited an initial apparent modulus, progressive modulus reduction, strain accumulation and S-N curve behaviour similar to human and animal vertebral cancellous bone. Synthetic open-cell foam vertebrae offer researchers an alternative to human vertebral bone for static and dynamic biomechanical experiments, including studies examining the effects of cement injection. Presented, in part, at the XXth Congress of the International Society of Biomechanics and 29th Annual Meeting of the American Society of Biomechanics, Cleveland, OH, July 31-August 5, 2005     

Domain-Decomposition Singular Boundary Method for Stress Analysis in Multi-Layered Elastic Materials

This paper applies an improved singular boundary method (SBM) in conjunction with domain decomposition technique to stress analysis of layered elastic materials. For problems under consideration, the interface continuity conditions are approximated in the same manner as the boundary conditions. The multi-layered coating system is decomposed into multiple subdomains in terms of each layer, in which the solution is approximated separately by the SBM representation. The singular boundary method is a recent meshless boundary collocation method, in which the origin intensity factor plays a key role for its accuracy and efficiency. This study also introduces new strong-form regularization formulas to accurately evaluate the origin intensity factors for elasticity problem. Consequently, we dramatically improve the accuracy and convergence of SBM solution of the elastostatics problems. The proposed domain-decomposition SBM is tested on two benchmark problems. Based on numerical results, we discuss merits of the present SBM scheme over the other boundary discretization methods, such as the method of fundamental solution (MFS) and the boundary element method (BEM).     

Osteoblast proliferation on neat and apatite-like calcium phosphate-coated titanium foam scaffolds

The biocompatibility and the load-bearing ability of lightweight titanium made it possible to be used as a biomaterial, especially in hip revision and fixation surgery. It was initially shown that sand-blasted or surface-roughened titanium implants had an improved bone-bonding ability over the bioinert metallic surfaces. Plasma-spraying of a phase mixture of loosely-attached calcium phosphates on titanium implants further improved their in vivo bone-bonding ability. However, stoichiometric calcium hydroxyapatite ceramic of high crystallinity is known to have poor in vivo resorbability, and is shy of taking part in bone remodeling and of being resorbed by the osteoclasts. Supersaturated calcium phosphate (CaP) solutions, such as synthetic body fluids (SBF), on the other hand, are able to form “carbonated, hydrophilic and apatite-like” CaP nanoaggregates on titanium surfaces. A Tris-buffered SBF solution with an HCO₃⁻ concentration of 27 mM was used in this study. Neat, NaOH-etched, and SBF-coated (biomimetic coating) titanium foams were compared with in vitro cell culture experiments by using rat osteoblasts. SBF-coated foams were found to yield the highest protein concentration at the end of the in vitro culture tests. Such biomimetic coatings were easily formed on flat strips, springs, or 3D foams of titanium, without any geometric constraints. The coated titanium springs and foams were characterized by using XRD, SEM, and FTIR.     

In vitro analysis of polyurethane foam as a topical hemostatic agent

Topical hemostatic agents can be used to treat problematic bleedings in patients who undergo surgery. Widely used are the collagen- and gelatin-based hemostats. This study aimed to develop a fully synthetic, biodegradable hemostatic agent to avoid exposure to animal antigens. In this in vitro study the suitability of different newly developed polyurethane-based foams as a hemostatic agent has been evaluated and compared to commonly used agents. An experimental in vitro test model was used in which human blood flowed through the test material. Different modified polyurethane foams were compared to collagen and gelatin. The best coagulation was achieved with collagen. The results of the polyurethane foam improved significantly by increasing the amount of polyethylene glycol. Therefore, the increase of the PEG concentration seems a promising approach. Additional in vivo studies will have to be implemented to assess the application of polyurethane foam as a topical hemostatic agent.