离网型同步风力发电机单位功率因数新型控制策略

针对离网型直驱永磁风电系统机侧变换器无功容量过大问题,提出了一种永磁同步风力发电机单位功率因数新型控制策略.该控制策略首先是将同步旋转坐标系基于永磁同步电机转子磁场定向,其次求解出无功为零时的d轴电流isd,通过分析isd和永磁同步电机的空间矢量,设计出永磁同步电机矢量控制下的一种新型的isd直接给定方案.为了减小谐波...     

基于改进LS-ESPRIT算法的GTD模型参数估计与RCS重构

针对传统LS-ESPRIT算法在估计GTD模型参数时抗噪效果差,估计精度不高这一问题,该文提出了一种改进的LS-ESPRT算法,有效地提高了算法的参数估计性能与抗噪性。首先,根据雷达目标的回波数据构建Hankel矩阵;其次,采用核范数凸优化方法对上述Hankel矩阵进行降噪处理,得到低秩的重构Hankel矩阵;最后,利用传统的LS-ESPRIT算法对降噪后的数据进行处理,估计出GTD模型参数。基于改进算法与传统算法分别得到重构RCS,并针对不同带宽对参数估计精度的影响作以仿真探究。仿真结果表明,与传统LS-ESPRIT算法与传统TLS-ESPRIT算法相比,改进LS-ESPRIT算法的参数估计性能更高,抗噪性更强,且重构RCS的幅值与相角误差更小。对不同带宽下的参数估计精度也进行了探究,并得出：带宽越大,估计精度越高。     

煤炭企业提高质量管理体系内部审核有效性浅析

通过实施有效的内部审核,可以提高质量管理体系的符合性和有效性,企业就可以形成良好的自我改进和自我完善的机制。但在很多煤炭企业中内部审核还存着一些问题。该文简要分析了煤炭企业内部审核存在问题的原因并提出一些提高内部审核有效性的途径。     

Interstitial Hydrogen Atom to Boost Intrinsic Catalytic Activity of Tungsten Oxide for Hydrogen Evolution Reaction

Tungsten oxide (WO₃) is an appealing electrocatalyst for the hydrogen evolution reaction (HER) owing to its cost-effectiveness and structural adjustability. However, the WO₃ electrocatalyst displays undesirable intrinsic activity for the HER, which originates from the strong hydrogen adsorption energy. Herein, for effective defect engineering, a hydrogen atom inserted into the interstitial lattice site of tungsten oxide (H_0.23WO₃) is proposed to enhance the catalytic activity by adjusting the surface electronic structure and weakening the hydrogen adsorption energy. Experimentally, the H_0.23WO₃ electrocatalyst is successfully prepared on reduced graphene oxide. It exhibits significantly improved electrocatalytic activity for HER, with a low overpotential of 33 mV to drive a current density of 10 mA cm⁻² and ultra-long catalytic stability at high-throughput hydrogen output (200 000 s, 90 mA cm⁻²) in acidic media. Theoretically, density functional theory calculations indicate that strong interactions between interstitial hydrogen and lattice oxygen lower the electron density distributions of the d-orbitals of the active tungsten (W) centers to weaken the adsorption of hydrogen intermediates on W-sites, thereby sufficiently promoting fast desorption from the catalyst surface. This work enriches defect engineering to modulate the electron structure and provides a new pathway for the rational design of efficient catalysts for HER.     

核桃内源性多酚的体外抗氧化能力及对核桃油 氧化稳定性的影响

为促进核桃加工副产物的综合利用,探究副产物中多酚对核桃油氧化稳定性的影响,测定了槲皮素、没食子酸、儿茶素、绿原酸、鞣花酸5种核桃内源性多酚对DPPH和ABTS+自由基的清除能力及氧自由基吸收能力（ORAC）以评价其体外抗氧化能力,并将5种内源性多酚分别加入核桃油中,进行18 d的加速氧化试验,以酸值、过氧化值、共轭二烯值、共轭三烯值、同步荧光光谱、色泽及感官品质（透明度、气味、滋味）作为考察指标,分析其对核桃油氧化稳定性的影响。结果表明：槲皮素、没食子酸和绿原酸的体外抗氧化能力较强;5种多酚均能有效减缓核桃油酸值、过氧化值、共轭二烯值和共轭三烯值的升高,其中没食子酸、绿原酸和儿茶素在维持核桃油感官品质方面优于其他2种多酚。综上,在开发核桃油相关产品时,可以考虑通过添加没食子酸、儿茶素和绿原酸提高产品的氧化稳定性。     

有机磷光体系及其研究进展

室温磷光性有机物由于三重态激子的参与和相对较慢的衰变速率，使其具有较长波长及长寿命的特性，让该类型化合物在光学器件、光催化反应、生物成像等领域中具有广泛的应用前景。目前构筑室温磷光有机体系主要是通过促进自旋轨道耦合和抑制三重态到基态的非辐射衰变来完成。对近年来室温磷光有机体系的发展进行归纳和总结，针对如何设计室温磷光有机体系提出了几种方法，并分析其原理，对未来室温磷光有机体系的发展与应用进行了展望。     

嵌入轻量梯度提升机评估模型的暂态稳定预防-紧急协调控制

为了综合发挥运行方式控制和稳控切机控制对电网暂态稳定性的提升作用,提出一种嵌入轻量梯度提升机(light gradient boosting machine,LightGBM)评估模型的电力系统暂态稳定预防-紧急协调控制决策方法。为快速评估控制措施对稳定裕度的影响,首先利用混合控制样本生成方法和LightGBM算法构建预防-紧急控制对稳定裕度的评估模型,考虑到不合理的切机、切负荷控制可能破坏系统稳定性,利用LightGBM评估模型的数值灵敏度来辨识有效的控制地点、缩减决策空间。进一步将LightGBM模型嵌入暂态稳定双层优化控制模型、替代暂态稳定时域仿真校核,结合改进的非支配排序遗传算法(non-dominated sorting genetic algorithm-Ⅱ,NSGA-Ⅱ)实现协调控制策略的快速求解。通过IEEE 39节点测试算例,验证了所提方法能够实现不同严重程度的故障在发生前后的预防控制和紧急控制之间的协调配合,既提高了电网安全稳定性,又减小了优化调度成本。     

A Diagnostic and Therapeutic Hydrogel to Promote Vascularization via Blood Sugar Reduction for Wound Healing

Chronic hyperglycemic damage is a major problem that undermines diabetic wound healing. By combining treatment and diagnosis together, blood glucose concentration can be monitored real-time through medical imaging devices and precise interventions can be carried out at the right time to promote diabetic wound repair. In this study, an injectable self-healing hyaluronic acid hydrogel is constructed using Schiff base reaction, and nanoenzymes (GOx-MnO₂) synthesized by condensation reaction, along with vascular endothelial growth factor (VEGF)-nanobubbles produced by double emulsification method, are loaded into the hydrogel, thus constructing an innovative diagnostic and therapeutic hydrogel system (US@GOx@VEGF hydrogel, UGV hydrogel). While monitoring glucose concentration in real-time, the system delivers VEGF through ultrasound in a precise and noninvasive way to deplete glucose. The UGV hydrogel integrates both processes of diagnosis and treatment, effectively releases VEGF through blasts triggered by ultrasound. Apart from this, this new trauma patch is capable of monitoring Mn²⁺ values ranging from 0.5 m to 7.8 × 10⁻³ m and glucose levels from 100 × 10⁻³ to 3 × 10⁻³ m , through magnetic resonance imaging. In summary, the hydrogel realizes real-time monitoring of glucose level, maintains glucose homeostasis through noninvasive intervention, and rapidly promotes the repair of diabetic skin defects, opening up a new path for chronic wound management.     

Nitric Oxide Generation and Endothelial Progenitor Cells Recruitment for Improving Hemocompatibility and Accelerating Endothelialization of Tissue Engineering Heart Valve

Tissue engineering heart valve (TEHV) offers great potential to overcome the limitations of commercial artificial valves used in clinical practice as a permanent prosthetic valve. Currently, decellularized heart valve (DHV) is the most widely used scaffold for TEHV, but showed suboptimal performance due to difficulty of endothelialization. Facilitating endothelialization of DHV is indispensable for better valve performance, and excellent hemocompatibility guarantees enough time windows for endothelialization process. Herein, a dual-functional TEHV scaffold with improving hemocompatibility and accelerating endothelialization is constructed by modifying DHV with copper ions (Cu) and growth differentiation factor 11 (GDF11). Results show the newly-constructed scaffold successfully generates endogenous nitric oxide (NO) through catalysis of Cu, and possesses improved hemocompatibility by down-regulating platelets activation and adhesion. Furthermore, GDF11 immobilization significantly accelerates scaffold endothelialization through facilitating recruitment, supporting growth, and alleviating apoptosis of endothelial progenitor cells . This TEHV scaffold shows favorable performance under in vivo hemodynamic environment with intact endothelial coverage and adaptive ECM remodeling, and without thrombus or calcification formation. This newly-constructed TEHV scaffold is expected to make up for the shortcomings of currently available prosthetic valves in clinical practice and has the potential possibility of rapid translation to the clinic as a better prosthetic valve.     

溃堤洪水在有压雨水管网街区演进的试验研究

溃堤洪水在有压雨水管网街区的演进过程十分复杂，城市街区建筑物及雨水管网改变了洪水的演进规律，影响了街区排涝的水力特性。本文基于典型城市街区建立了包括房屋、人行道及雨水管网在内的概化水槽模型，测量了不同溃堤洪水在典型城市街区演进过程中的街区水深、雨水管网流量及压强，探究了不同蓄水高度、前池进口流量对街区水位波动变化及有压雨水管网下泄流量的影响。溃堤洪水在水槽侧壁、房屋的作用下形成了大面积的水跃，并且在房屋建筑物附近出现了薄层状水片，水跃区域伴随着洪水演进过程先是在人行道处发生横向的迁移合并，再是在街区道路的纵向方向上逐渐耗散直至消失，街区水位在100 s后基本稳定，从上游至下游呈“先增大、再减小”的变化趋势。溃堤洪水在街区演进过程中，不同蓄水高度对有压雨水管网的泄流量影响相较于不同前池进口流量更加显著，街区上游雨水口的峰值流量在最大蓄水高度条件约为最大前池进口流量的1.5倍。研究结合街区水位及有压雨水管网压强采用欧拉数对短管淹没出流公式的泄流系数进行了率定，修正后的理论计算值的误差由32%降低至2%，能够较好地反映出街区雨水口的泄流能力。研究成果不仅能为数学模型提供翔实的验证资料，还可为城市洪涝治理提供理论指导。