中国国际贸易中心三期A主塔楼结构设计

位于北京的中国国际贸易中心三期主塔楼高330m,包括一座五星级酒店和甲级写字楼。结构设计的主要难点是在北京这一高烈度地区建设超高层大楼,如何能综合考虑结构的安全性与经济性的要求,在结构设计过程中,各种结构类型及不同材料的使用都经过讨论研究。最终的结构体系是一个组合支撑框架核心筒和组合周边刚性框架筒,在机电层再辅以伸臂桁架连接内外筒。由于塔楼外立面宽度逐渐收小,结构上采用了3层腰桁架,而在腰桁架之间柱子的数量逐渐减少。塔楼的底部是8层高带转换桁架的V型柱,既符合建筑上对五星级酒店和甲级写字楼首层宏大的主入口的要求,同时又可平缓地过渡到上部的抗弯刚架。结构体系中根据不同的部位相对采用了各种类型的组合构件来满足刚度,延性以及冗余度的要求,并达到最好的性能价格比。工程大规模应用了组合钢板墙(C-SPW)这一新型结构体系,以增加剪力墙的抗剪承载力和刚度,并改善延性。结构设计中运用了有限元分析及非线性弹塑性时程分析来评估结构的     

Normal and pathological NCAT image and phantom data based on physiologically realistic left ventricle finite-element models

The four-dimensional (4-D) NURBS-based cardiac-torso (NCAT) phantom, which provides a realistic model of the normal human anatomy and cardiac and respiratory motions, is used in medical imaging research to evaluate and improve imaging devices and techniques, especially dynamic cardiac applications. One limitation of the phantom is that it lacks the ability to accurately simulate altered functions of the heart that result from cardiac pathologies such as coronary artery disease (CAD). The goal of this work was to enhance the 4-D NCAT phantom by incorporating a physiologically based, finite-element (FE) mechanical model of the left ventricle (LV) to simulate both normal and abnormal cardiac motions. The geometry of the FE mechanical model was based on gated high-resolution X-ray multislice computed tomography (MSCT) data of a healthy male subject. The myocardial wall was represented as a transversely isotropic hyperelastic material, with the fiber angle varying from -90 degrees at the epicardial surface, through 0 degrees at the midwall, to 90 degrees at the endocardial surface. A time-varying elastance model was used to simulate fiber contraction, and physiological intraventricular systolic pressure-time curves were applied to simulate the cardiac motion over the entire cardiac cycle. To demonstrate the ability of the FE mechanical model to accurately simulate the normal cardiac motion as well as the abnormal motions indicative of CAD, a normal case and two pathologic cases were simulated and analyzed. In the first pathologic model, a subendocardial anterior ischemic region was defined. A second model was created with a transmural ischemic region defined in the same location. The FE-based deformations were incorporated into the 4-D NCAT cardiac model through the control points that define the cardiac structures in the phantom which were set to move according to the predictions of the mechanical model. A simulation study was performed using the FE-NCAT combination to investigate how the differences in contractile function between the subendocardial and transmural infarcts manifest themselves in myocardial Single photon emission computed tomography (SPECT) images. The normal FE model produced strain distributions that were consistent with those reported in the literature and a motion consistent with that defined in the normal 4-D NCAT beating heart model based on tagged magnetic resonance imaging (MRI) data. The addition of a subendocardial ischemic region changed the average transmural circumferential strain from a contractile value of -0.09 to a tensile value of 0.02. The addition of a transmural ischemic region changed average circumferential strain to a value of 0.13, which is consistent with data reported in the literature. Model results demonstrated differences in contractile function between subendocardial and transmural infarcts and how these differences in function are documented in simulated myocardial SPECT images produced using the 4-D NCAT phantom. Compared with the original NCAT beating heart model, the FE mechanical model produced a more accurate simulation for the cardiac motion abnormalities. Such a model, when incorporated into the 4-D NCAT phantom, has great potential for use in cardiac imaging research. With its enhanced physiologically based cardiac model, the 4-D NCAT phantom can be used to simulate realistic, predictive imaging data of a patient population with varying whole-body anatomy and with varying healthy and diseased states of the heart that will provide a known truth from which to evaluate and improve existing and emerging 4-D imaging techniques used in the diagnosis of cardiac disease.     

Soft-Computing-Based Embedded Design of an Intelligent Wall/Lane-Following Vehicle

Soft computing techniques are generally well suited for vehicular control systems that are usually modeled by highly nonlinear differential equations and working in unstructured environments. To demonstrate their applicability in real-world applications, two intelligent controllers based on fuzzy logic and artificial neural network are designed for performing a wall-following task. Based on performance and flexibility considerations, the two controllers are implemented onto a reconfigurable hardware platform, namely a field-programmable gate array. As comparative studies of these two embedded hardware controllers designed for the same vehicular application are limited in literature, this research also presents an evaluation of the two controllers, comparing them in terms of hardware resource requirements, operational speeds, and trajectory tracking errors in following different predefined trajectories.     

Crystallization behavior of polylactide matrix under the influence of nano‐magnetite

Iron oxide nanoparticle (Fe₃O₄) has gained remarkable research interest for various applications, from environmental to biological, because of its superparamagnetic properties and good biocompatibility. In this work, the nucleation effect of Fe₃O₄ in a polylactide (PLA) matrix under an influence of an alternating magnetic field was studied. The nanocomposite films that is, containing different concentrations of Fe₃O₄ (~8 nm) which were uniformly dispersed in the PLA matrix, were prepared via a solution casting method. The amplitude and frequency of the magnetic field impose great effects on the morphology and nucleation rate of PLA crystallization. Thermogravimetric analysis was used to study the thermal stability of Fe₃O₄/PLA and it showed that the thermal stability of Fe₃O₄/PLA was affected by the Fe₃O₄ content. Fourier transform infrared spectroscopy and X‐ray diffractometry indicated that Fe₃O₄ shows impeding effect to the crystallization of PLA. Based on the differential scanning calorimetry results, composite with 1% of Fe₃O₄ content could promote the crystallization of PLA but it would become an obstacle when 3% of Fe₃O₄ was added. The result of polarized optical microscopy also showed a good agreement that the incorporation of Fe₃O₄ could act as an effective nucleation regent to the composite film. POLYM. ENG. SCI., 59:608–615, 2019. © 2018 Society of Plastics Engineers     

Extract of white button mushroom affects skin healing and angiogenesis

White button mushroom extract was examined in this study on (1) its potential effect on angiogenesis in chorioallantoic culture and (2) its recovering effect on the skin after injury in the ICR mice. Methods used included TUNEL assay on apoptosis, immunohistochemistry for vascular endothelial growth factor (VEGF), proliferative cell nuclear antigen (PCNA), epidermal growth factor (EGF), transforming growth factor β (TGF‐β), and immune factor CD4 and western blotting. The results of chorioallantoic culture showed that the mushroom treatment led to significant increase in densities of VEGF sites. In the skin injury, ICR mice model increased EGF, PCNA, and collagen fibers, along with decrease of TUNEL positive apoptotic cells and limited reaction of TGF‐β and CD4 indicated that white button mushroom extract appeared to have beneficial effects on skin in regeneration and after injury. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.     

Large-scale,adhesive-free and omnidirectional 3D nanocone anti-reflection films for high performance photovoltaics

An effective and low-cost front-side anti-reflection(AR) technique has long been sought to enhance the performance of highly efficient photovoltaic devices due to its capability of maximizing the light absorption in photovoltaic devices. In order to achieve high throughput fabrication of nanostructured flexible and anti-reflection films, large-scale, nano-engineered wafer molds were fabricated in this work. Additionally, to gain in-depth understanding of the optical and electrical performance enhancement with AR films on polycrystalline Si solar cells, both theoretical and experimental studies were performed. Intriguingly,the nanocone structures demonstrated an efficient light trapping effect which reduced the surface reflection of a solar cell by17.7% and therefore enhanced the overall electric output power of photovoltaic devices by 6% at normal light incidence. Notably, the output power improvement is even more significant at a larger light incident angle which is practically meaningful for daily operation of solar panels. The application of the developed AR films is not only limited to crystalline Si solar cells explored here, but also compatible with any types of photovoltaic technology for performance enhancement.     

Optimization strategy for encapsulation efficiency and size of drug loaded silica xerogel/polymer core‐shell composite nanoparticles prepared by gelation‐emulsion method

It has been commonly discovered that reducing particle size always accompanies with undesirable deterioration of drug encapsulation efficiency in double emulsion based techniques. However, a clear optimization strategy for process variables to minimize this negative impact has been rarely reported. To fill this gap, we have successfully developed an optimization strategy for silica xerogel/polymer composite nanoparticles prepared by our recently developed gelation‐emulsion method. To develop this strategy, interactive effects of multiple process variables were investigated through a four‐factor three‐level experimental design by considering all screened dominant process variables influencing particle size and encapsulation efficiency, including sonication time of second emulsion (t₂), sonication power of the second emulsion (P₂), total volume of the second emulsion (V₂) and volume ratio of aqueous phase and primary emulsion (r). The optimization strategy for fabricating the target particle size with optimal encapsulation efficiency was designed by adjusting the process variables in the order of r, V₂, t₂, and P₂ With this strategy, conspicuous enhancement of the encapsulation efficiency (e.g., from 27 to 63% for a particle size of 211 nm) and significant increment of the feasible size range through our novel fabrication method from 192–569 nm to 90–914 nm have been achieved in this study. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers     

一种用于岩石材料微裂纹观察的复型技术

介绍了一种用于岩石材料微裂纹观察的复型技术。这种半透明的试样表面复型可有效复制宽度大于0.2μm的微观裂纹以及矿物颗粒的微结构特征，并可方便地用于光学显微镜和扫描电镜下观察。它的最大特点是不仅能精确复制岩样的表面裂纹，同时还能提供足够多的信息以鉴别矿物颗粒。应用表明：对于岩石材料的微破裂研究，特别对于矿物颗粒的破坏行为与岩石破坏的关系研究，它是一种方便而有效的方法。     

Discrete Element Modeling of Contact Creep and Aging in Sand

In this study, aging in dry, clean sand induced by contact creep is investigated through numerical simulations using the discrete element method. Simulation results demonstrate that contact creep initiates the redistribution of contact forces. Although contact creep produces a very small decrease in porosity (approximately 1.7%), a significant change in the contact force distribution is produced in the aged sample. The contact forces ultimately become more uniform in both magnitude and spatial distribution. This homogenization of contact forces leads to more stable force chains and therefore produces an increase in the small-strain stiffness, early strength, and dilatancy in the aged sample. Such increases are not found in the sample prepared to the same porosity as the aged sample but without aging. This is because, in generating this sample, the contact creep is not allowed and therefore its associated contact force distribution is less homogenized compared with that in the aged sample.     

Effect of compost age and composition on the atrazine removal from solution

Compost samples from two composting facilities, the Urbana (Illinois) Landscape Recycling Center (ULRC) and Illinois State University (ISU), were selected to examine the effect of compost age on atrazine removal from solution. The ULRC samples were made from yard waste without an additional nitrogen source. The ISU samples were made from yard waste or sawdust with the addition of manure. The 6-month-old ULRC compost had the greater capacity to remove atrazine from solution, which we attributed to its greater organic carbon content. The addition of nitrate into ULRC compost could influence the extent of atrazine removal, but did not have a significant impact on atrazine removal when applied to ISU compost, probably because manure was added to the yard waste to produce the compost. For both ULRC and ISU samples, the presence of sodium azide inhibited atrazine removal, suggesting that microbial activity contributed to the atrazine removal. Metabolic analysis demonstrated that hydroxyatrazine was the major identified metabolite that accumulated in solution before significant ring mineralization could occur. When compared with the ISU compost, the ULRC compost sample had a greater capacity to remove atrazine from solution during the 120 days of study because of the larger humic acid content. The experimental results suggested that less-mature compost may be better suited for environmental applications such as removing atrazine from tile-drainage waters.