Stacked Pyramid Attention Network for Object Detection

Neural Processing Letters - Scale variation is one of the primary challenges in object detection. Recently, different strategies have been introduced to address this challenge, achieving promising...     

三种熏蒸剂在果蔬保鲜中应用的研究进展

果蔬在采后以及贮藏过程中易发生氧化褐变、组织软化、腐烂变质等生理生化变化,造成果蔬品质下降、经济损失和资源的浪费,因此,果蔬保鲜技术的研究与应用显得尤为重要。熏蒸技术主要是利用熏蒸剂在密闭空间内以气态形式扩散并与果蔬作用,通过调控多酚氧化酶(PPO)、过氧化物酶(POD)和超氧化物歧化酶(SOD)等酶活性、抑制细菌生长等方面发挥保鲜作用。本文主要综述了近年来普遍使用的乙醇、一氧化氮和植物精油等熏蒸剂在果蔬保鲜中应用研究进展,为果蔬保鲜研究中熏蒸剂的选择与熏蒸技术的应用提供理论依据。     

Comfort design and optimization of direct expansion multi-connected radiant air conditioning based on 3D flow field simulation

The air conditioning method based on radiation heat exchange has the characteristics of small vertical temperature gradient, high thermal comfort and energy saving, and has become a hot spot of attention. The Fluent numerical simulation, the experiment in this paper studies the direct expansion multi-line radiant air conditioner under the artificially simulated climate environment in winter heating, summer cooling and dehumidification. The temperature difference of the radiation + fresh air mode at the same time indoors under heating conditions is less than 2.5 °C, and the time to reach the indoor set temperature of 24 °C is about 2–3 h. Under cooling conditions, the temperature difference of the radiation + fresh air mode at the same time in the room is about 0.5–2 °C, and the time to reach the indoor set temperature of 26 °C is about 1–3 h. In the fresh air mode, the indoor temperature difference and response time at the same time are slightly larger than the radiation + fresh air mode. The freezing and dehumidification effect of fresh air is obvious, the moisture content of dehumidifying fresh air is between 6.3 and 10.5 g/kg, and the dehumidification efficiency can reach 50%. Under the same artificial simulated climate environment, the consumption of the three modes is not much different. When the outdoor temperature in heating conditions is higher than 9 °C, the fresh air mode can get better, and the radiation + fresh air mode can achieve better comfort when running indoors under various conditions.     

高效液相色谱法测定纺织品中喹啉的质量浓度

建立了测定纺织品中喹啉质量浓度的高效液相色谱检测方法,用高效液相色谱仪对样品中的喹啉及其他组分进行分离,用二极管阵列检测器进行紫外光谱分析,用峰面积外标法进行定量。喹啉的检出限为10 mg/kg,回收率在80%~120%,精密度小于2%。结果表明,该方法线性良好,测试简单,回收率、精密度高,满足测试要求。     

Improved multi-recessed 4H–SiC MESFETs with double-recessed p-buffer layer

An improved multi-recessed 4H–SiC metal semiconductor field effect transistor (MRD-MESFET) with double-recessed p-buffer layer (DRB-MESFET) is proposed in this paper. By introducing a double-recessed p-buffer layer, the gate depletion layer is further modulated, and higher drain saturation current and DC transconductance are obtained compared with the MRD-MESFET. The simulations show that the drain saturation current of the DRB-MESFET is about 42.4% larger than that of the MRD-MESFET. The DC transconductance of the DRB-MESFET is almost 15% higher than that of the MRD-MESFET and very close to that of double-recessed structure (DR-MESFET) at the bias conditions of V_gs=0 V and V_ds=40 V. The proposed structure has an improvement of 26.1% and 74.2% in the output maximum power density compared with that of the MRD-MESFET and DR-MESFET, respectively. In the meanwhile, the proposed structure possesses smaller gate-source capacitance, which results in better RF characteristics.     

云苓水溶性化学成分的研究

对茯苓的水溶性化学成分进行研究,从而为阐明茯苓的药效物质基础提供理论依据。采用D101大孔树脂、硅胶柱层析、ODS等方法对茯苓的水溶性化学成分进行分离纯化,并通过1H-NMR、13C-NMR对化合物进行结构鉴定。结果表明:从茯苓水提物中分离并鉴定了3个化合物,分别为:酪氨酸(Ⅰ)、苯丙氨酸(Ⅱ)、3-吲哚乙醇(Ⅲ)。结论:化合物(Ⅰ)~(Ⅲ)均为首次从茯苓中分离得到。     

氨合成塔支撑结构比较与挂式支座有限元分析简

氨合成塔设备庞大,重量大。对于承受重量、风载荷、地震载荷作用下挂式支座,现有标准没有成熟的计算方法;本文通过对焊接裙座和挂式支座对比,利用ANSYS对这种结构支座建立了有限元模型,使用MPC法加载后对结构支座进行了整体应力分析和焊缝应力分析,给出了相应部位的应力分布图,为做类似产品的设计者提供参考借鉴。     

燃气机热泵空调系统的实际应用

介绍了燃气机热泵空调室外机的结构。结合工程实例,探讨了燃气机热泵空调系统的设计,介绍了使用燃气机热泵空调系统的体会。分析了燃气机热泵空调系统与常规热泵空调系统、集中供暖系统相比具有的优势。     

Polyaniline-graphene composites with a three-dimensional array-based nanostructure for high-performance supercapacitors

The ordered three-dimensional arrays conjugative polyaniline–graphene composites were fabricated through in-situ chemical oxidative polymerization of aniline in the presence of amino-functionalized graphene sheets (AFG), in which polyaniline (PANI) polymerization is initiated by those amino groups on graphene. Therefore, the resulting PANI nanorod arrays are integrated into a large conjugative frame based on chemical covalent bond incorporation. The structure and properties of these resulting composites were characterized and evaluated by combining Fourier transform infrared spectroscopy, Ultraviolet–visible absorption spectroscopy, Raman spectroscope, X-ray diffraction spectroscopy analyses and electrochemical techniques. Morphology was studied by scanning electron microscopy. It was found that the density and size of ordered PANI nanorod arrays can be manipulated by simply varying the amount of AFG. Such resultant composite exhibits high special capacitance, together with low electrical resistance and excellent cycling stability attributed to conjugative covalent bonds and ordered PANI nanorod arrays. Meanwhile, a new time-dependent heterogeneous nucleation mechanism was proposed and investigated in detail.     

LNG接收站次氯酸钠投加量确定及产生装置选择

LNG接收站通常采用海水作为气化LNG的热媒,但实际运行中,却存在海洋微生物滋生、附着管道及设备的风险。因此,LNG接收站通常会在海水取水口处投加次氯酸钠(NaClO),但NaClO投加量及产生装置却是其必须考虑的问题。首先,分析了投加量的影响因素及评价标准,并以大连LNG接收站为例说明投加量的具体确定方法;其次,分析了电解海水制NaClO装置及NaClO溶液直接投加装置,并计算了二者的运行成本;最后,就两种装置的优劣进行对比分析。结果显示,电解海水制NaClO装置具有运行成本低、NaClO即产即用的优点;而NaClO溶液直接投加装置则具有前期投资费用低、装置简单和建造面积小的优点。