高漏偏压下AlGaN/GaN HEMT噪声性能的研究

The advent of fully integrated GaN PA-LNA circuits makes it meaningful to investigate the noise performance under high drain bias. However, noise performance of AlGaN/GaN HEMTs under high bias has not received worldwide attention in theoretical studies due to its complicated mechanisms. The noise value is moderately higher and its rate of increase is fast with increasing high voltage. In this paper, several possible mechanisms are proposed to be responsible for it. Impact ionization under high electric field incurs great fluctuation of carrier density, which increases the drain diffusion noise. Besides, higher gate leakage current related shot noise and a more severe self-heating effect are also contributors to the noise increase at high bias. Analysis from macroscopic and microscopic perspectives can help us to design new device structures to improve noise performance of AlGaN/GaN HEMTs under high bias.     

以课题制为核心的化工专业实习方式改革与实践

为培养学生的工程素质,我校化工专业采用以课题制为核心的实习方式,将企业生产中的工程问题梳理、凝练成小课题,让学生分组完成,企业技术人员和学校教师共同指导,采用课题报告、答辩、过程表现、安全知识考核等评价学习效果。这种实习方式能有效培养学生的自学能力和研究能力,增强学生的团队合作、沟通交流能力和社会责任感,显著提高学生的工程素质,有助于学生在学科竞赛和课程学习中取得优异的成绩。     

SHPB试验中合理加载波形比选分析

针对SHPB试验中如何选择合理加载波形问题,将矩形波、坡形波、三角波和常规梯形波等入射波形统一表达为不同升时的梯形波,并给出其加载应力路径方程。首先,计算分析了加载持续时间和最大应力幅值相同情况下,采用不同升时梯形波和半正弦波加载时,试件应力平衡时间t′_u随波阻抗比β变化情况,以及不同β的试件应力均匀性变化特征。其次,从试件应力平衡时间和应力均匀性角度分析两种加载波形的优劣性。升时t′_r=2、4的梯形波优于半正弦波,半正弦波优于t′_r≥7的梯形波;而t′_r=0、1、3、5、6的梯形波与半正弦波加载时t′_u曲线变化过程中出现了交叉现象,交叉前半正弦波优于此升时的梯形波,交叉后两者优劣性相反。最后,提出试验中合理加载波形的选择与确定。即无论β为何值,t′_r=2或4的梯形波加载时,试件均能获得较短应力平衡时间和较好应力均匀性,试验中应将t′_r=2的梯形波作为最佳加载波形优先选用,其次可考虑选用t′_r=4的梯形波;此外,计算给出不同β值对应的其他合理加载波形以便试验中选用。     

平装可转位球头立铣刀的研制

本文作者全面介绍了可转位球头立铣刀的设计理论,造型方法,制造手段,并介绍了样刀的切削试验和研制的球头立铣刀的特性.同时提出加工刀片槽的数学模型.     

Discriminant maximum margin projections for face recognition

Multimedia Tools and Applications - In this paper, we propose a novel dimensionality reduction algorithm called discriminant maximum margin projections (DMMP) for face recognition. By discovering...     

SPION‐Decorated Exosome Delivered BAY55‐9837 Targeting the Pancreas through Magnetism to Improve the Blood GLC Response

BAY55‐9837, a potential therapeutic peptide in the treatment of type 2 diabetes mellitus (T2DM), is capable of inducing glucose (GLC)‐dependent insulin secretion. However, the therapeutic benefit of BAY55‐9837 is limited by its short half‐life, lack of targeting ability, and poor blood GLC response. How to improve the blood GLC response of BAY55‐9837 is an existing problem that needs to be solved. In this study, a method for preparing BAY55‐9837‐loaded exosomes coupled with superparamagnetic iron oxide nanoparticle (SPIONs) with pancreas islet targeting activity and an enhanced blood GLC response with the help of an external magnetic force (MF) is demonstrated. The plasma half‐life of BAY55‐9837 loaded in exosome‐SPION is 27‐fold longer than that of BAY55‐9837. The active targeting property of SIPONs enables BAY‐exosomes to gain a favorable targeting property, which improves the BAY55‐9837 blood GLC response capacity with the help of an external MF. In vivo studies show that BAY‐loaded exosome‐based vehicle delivery enhances pancreas islet targeting under an external MF and markedly increases insulin secretion, thereby leading to the alleviation of hyperglycemia. The chronic administration of BAY‐exosome‐SPION/MF significantly improves glycosylated hemoglobin and lipid profiles. BAY‐exosome‐SPION/MF maybe a promising candidate for a peptide drug carrier for T2DM with a better blood GLC response.     

Promoting Energy Efficiency via a Self-Adaptive Evaporative Cooling Hydrogel

High temperature brings adverse impacts on the energy efficiency, and even destroys a semiconductor device. Here, a novel and cost-effective strategy is proposed to boost the energy efficiency of semiconductor devices by using the self-adaptive evaporative cooling of a lithium- and bromine-enriched polyacrylamide hydrogel. Water inside the hydrogel can quickly evaporate to dissipate the waste heat generated by the nugatory carrier transport in the P-N junction. In dormancy, the hydrogel harvests water molecules from the surrounding air to regenerate itself. The hydrogel is demonstrated to low down the operating temperature of a commercial polycrystalline silicon solar cell by 17 °C under one sun condition and enhances its efficiency from 14.5% to 15.5%. It is also capable of increasing the maximum power of a simulated chip by 45% at a fixed operating temperature. The hydrogel is expected to be widely adopted in current semiconductor industry to improve its energy efficiency.     

Multi-objective optimal design and performance of magnetorheological damper

In order to solve the problems of high power consumption and low output damping force of magnetorheological dampers, the relationship model between the structural parameters and the optimization objectives of dampers is established with the low power consumption and lightweight of magnetorheological dampers. The key structural parameters of the magnetorheological damper are optimized by the multi-objective genetic algorithm, and the optimal solution is obtained, and the optimized magnetorheological damper is tested and studied. The rationality of the selected parameters is verified by experimental study. The results show that the power consumption of magnetorheological dampers is reduced by 43 % and the damping force is increased by 30 % after optimization. There is a balance relationship between the power consumption optimization and the damping force optimization of the damper. Therefore, when finding the optimal solution, we should consider the needs of the actual situation and select the most reasonable parameters.     

Nanotransducers for Near‐Infrared Photoregulation in Biomedicine

Photoregulation, which utilizes light to remotely control biological events, provides a precise way to decipher biology and innovate in medicine; however, its potential is limited by the shallow tissue penetration and/or phototoxicity of ultraviolet (UV)/visible light that are required to match the optical responses of endogenous photosensitive substances. Thereby, biologically friendly near‐infrared (NIR) light with improved tissue penetration is desired for photoregulation. Since there are a few endogenous biomolecules absorbing or emitting light in the NIR region, the development of molecular transducers is essential to convert NIR light into the cues for regulation of biological events. In this regard, optical nanomaterials able to convert NIR light into UV/visible light, heat, or free radicals are suitable for this task. Here, the recent developments of optical nanotransducers for NIR‐light‐mediated photoregulation in medicine are summarized. The emerging applications, including photoregulation of neural activity, gene expression, and visual systems, as well as photochemical tissue bonding, are highlighted, along with the design principles of nanotransducers. Moreover, the current challenges and perspectives in this field are discussed.     

提高熔窑热效率的一点体会

2001年7月,一座运行了14年的500t熔窑放水冷修,利用此次冷修,我们进行了一些技术改造。在熔窑方面,引进了美国燃烧公司的油枪及其吹扫系统以改善燃烧和熔化质量,同时增加烟气脱硫以适应环保要求。