A comprehensive review of image analysis methods for microorganism counting: from classical image processing to deep learning approaches

Microorganisms such as bacteria and fungi play essential roles in many application fields, like biotechnique, medical technique and industrial domain. Microorganism counting techniques are crucial in microorganism analysis, helping biologists and related researchers quantitatively analyze the microorganisms and calculate their characteristics, such as biomass concentration and biological activity. However, traditional microorganism manual counting methods, such as plate counting method, hemocytometry and turbidimetry, are time-consuming, subjective and need complex operations, which are difficult to be applied in large-scale applications. In order to improve this situation, image analysis is applied for microorganism counting since the 1980s, which consists of digital image processing, image segmentation, image classification and suchlike. Image analysis-based microorganism counting methods are efficient comparing with traditional plate counting methods. In this article, we have studied the development of microorganism counting methods using digital image analysis. Firstly, the microorganisms are grouped as bacteria and other microorganisms. Then, the related articles are summarized based on image segmentation methods. Each part of the article is reviewed by methodologies. Moreover, commonly used image processing methods for microorganism counting are summarized and analyzed to find common technological points. More than 144 papers are outlined in this article. In conclusion, this paper provides new ideas for the future development trend of microorganism counting, and provides systematic suggestions for implementing integrated microorganism counting systems in the future. Researchers in other fields can refer to the techniques analyzed in this paper.

     

Distributed H∞ consensus control for nonlinear multi-agent systems under switching topologies via relative output feedback

Neural Computing and Applications - For a class of nonlinear multi-agent systems under switching topologies with disturbances, we propose a distributed H∞ consensus control protocol based on...     

Asymmetric CPW-fed SRR patch antenna for WLAN/WiMAX applications

In this paper, a compact asymmetric coplanar waveguide (CPW) feed with split-ring resonator (SRR) is proposed to resonate at dual-band operations for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The asymmetric CPW-fed SRR patch (ACSP) antenna consists of a meander line, square-shaped split ring, and CPW ground plane. The proposed ACSP antenna resonates at two operating frequencies, namely, 2.48 GHz (2.4–2.74 GHz) and 3.49 GHz (3.25–3.64 GHz) with reflection coefficients (S₁₁) of −16.65 dB and −32.67 dB, respectively. The measured results agree closely with the simulation results of the proposed antenna.     

雷达发射机浮动板调制器与故障检测电路的设计

提出了一种改进的浮动板调制器和对正负偏电压的故障检测电路,利用MOSFET寄生电容特性,通过固定脉宽窄脉冲控制调制脉宽,通过增加负偏MOSFET提高输出负偏电压。对故障检测电路进行仿真实验,通过模拟故障,验证故障检测报警信号发生时间均在微秒级别。完成样机的搭建,利用多重方式解决高压绝缘问题,并对其加电进行试验验证,分析实验波形,证明此电路满足设计要求并且具有可行性。     

Modified BCZN particles filled PTFE composites with high dielectric constant and low loss for microwave substrate applications

The modified 0.7Ba (Co_1/3Nb_2/3)O₃-0.3Ba(Zn_1/3Nb_2/3)O₃ (BCZN) powders filled PTFE composites were synthesized by hot-pressing. The influences of BCZN content on the microstructure, dielectric, thermal, mechanical properties and moisture absorption were investigated systematically. The modified BCZN powders filled PTFE composites exhibited better microstructure and dielectric properties compared with untreated powders. Various mathematic models were utilized to predict the dielectric constant of different composites and the effective medium theory (EMT) showed perfect consistency with the experimental results. The modified BCZN/PTFE composites possess the best comprehensive properties at the powders content of 50 vol% with high dielectric constant (ε_r) of 7.7, low loss (tanδ) of 0.0014, acceptable temperature coefficient of dielectric constant (τ_ε) of −125.6 ppm/°C and temperature coefficient of resonant frequency (τ_f) of 29.4 ppm/°C at 7 GHz, low moisture absorption of 0.07% and low coefficient of thermal expansion (CTE) of 33 ppm/°C. All the results show modified BCZN/PTFE composites are the potential materials for microwave substrate applications.     

Ultrathin MoSe2 three-dimensional nanospheres as high carriers transmission channel and full spectrum harvester toward excellent photocatalytic and photoelectrochemical performance

MoSe₂ ultrathin nanospheres with three-dimensional network structure (MSS) were prepared by improved solvothermal method. These MoSe₂ nanospheres are only 10 nm in size and actually composed of ultra-thin MoSe₂ nanosheets with a thickness of only 2–3 molecular layers. Compared with the MoSe₂ nanosheets (6–8 molecular layer thicknesses) of the three-dimensional flower structure (MSF) prepared by ordinary hydrothermal method, the MSS are thinner resulting in higher specific surface area of 5 times than that of MSF, and the light absorption ability at all UV–vis spectrum is stronger. The photocatalytic and photoelectrochemistry results show that the photocatalytic activity of MSS is 17 times that of the MSF, and the photoelectrochemical performance is twice. The results of electrochemical impedance spectroscopy and fluorescence spectroscopy confirmed that the MoSe₂ ultra-thin nanospheres with three-dimensional network structure have lower internal resistance and higher carrier transport and separation efficiency. In the most important three aspects that determine the photoelectrochemical performance of photocatalyst: specific surface area, light absorption capacity, carrier transport and separation efficiency, MSS exceed MSF. This three-dimensional network nanospheres structure can improve the performance of MoSe₂. This research successfully demonstrates the enhancement of the properties of MoSe₂ two-dimensional materials through structural regulation.     

Methanol steam reforming microreactor with novel 3D-Printed porous stainless steel support as catalyst support

In order to study the methanol steam reforming performance of the 3D-printed porous support for hydrogen production, three dimensional (3D) printing technology was proposed to fabricate porous stainless steel supports with body-centered cubic structure (BCCS) and face-centered cubic structure (FCCS). Catalyst loading strength of the 3D-printed porous stainless steel supports was studied. Moreover, methanol steam reforming performance of different 3D-printed porous supports for hydrogen production was experimentally investigated by changing reaction parameters. The results show that the 3D-printed porous stainless steel supports with BCCS and FCCS exhibit better catalyst loading strength, and can be used in the microreactor for methanol steam reforming for hydrogen production. Compared with 90 pores per inch (PPI) Fe-based foam support, 3D-printed porous stainless steel supports with FCCS and BCCS show the similar methanol steam reforming performance for hydrogen production in the condition of 6500 mL/(g·h) gas hourly space velocity (GHSV) with 360 °C reaction temperature. This work provides a new idea for the structural design and fabrication of the porous support for methanol steam reforming microreactor for hydrogen production.     

Thermal expansion coefficient tailoring of LAS glass-ceramic for anodic bondable low temperature co-fired ceramic application

The Li–Al–Si glass-ceramics were prepared by conventional glass-ceramic fabrication method. The influences of Na₂O content on the sintering property, microstructure, and coefficient of thermal expansion were investigated. The results show that the coefficient of thermal expansion of LAS glass-ceramics can be tailored to match that of silicon by the addition of Na₂O content. Na₂O has a remarkable influence on the crystallinity of Li–Al–Si glass-ceramic. The coefficient of thermal expansion of Li–Al–Si glass-ceramic is thus tunable between that of glass phase and crystal phase. The Si–O bond length change in stretch vibration modes introduced by Na₂O also contributes to the variation of coefficient of thermal expansion of the Li–Al–Si glass-ceramics. The coefficient of thermal expansion of the Li–Al–Si glass-ceramic with 1.5 wt% Na₂O addition is about +3.34 ppm/°C at 350 °C and shows a good compatibility to that of silicon in a wide temperature range, which makes it a promising candidate for anodic bondable low temperature co-fired ceramic substrate applications.     

计及损耗的双馈感应风力发电机高电压穿越控制策略

利用换向原理分析其电磁暂态特性，在此基础上，对DFIG输出无功功率与其铜损耗的解析关系进行了理论分析，推导出了使铜损耗最低的DFIG输出无功功率最优参考值。同时，转子的瞬时功率补偿分量减小了DC总线电压的波动，从而减少了转换器的功率损耗。由此，提出了考虑DFIG铜损和转换器损耗的DFIG高电压穿越控制策略。仿真结果表明，该控制策略可以在保证DFIG高电压穿越能力的同时降低DFIG铜损耗与换流器损耗，并具有较好的暂态特性。