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To deal with the poor generalization of previous deep learning-based methods, a novel anchor-free deep learning framework called CA-CentripetalNet is proposed for hardhat wearing detection. Two novel schemes are proposed to improve the feature extraction and utilization ability of CA-CentripetalNet, which are vertical-horizontal corner pooling and bounding constrained center attention. The former is designed to realize the comprehensive utilization of marginal features and internal features. The latter is designed to enforce the backbone to pay attention to internal features, which is only used during the training rather than during the detection. Experimental results indicate that the CA-CentripetalNet achieves better performance with the 88.63% mAP (mean Average Precision) with less memory consumption at a reasonable speed than the existing deep learning-based methods, especially in case of small-scale hardhats and non-worn-hardhats. [ABSTRACT FROM AUTHOR]

Microbial-mineral interaction has a broad application prospect in the field of environmental remediation of organic pollutants. However, the disadvantages of long repair cycle and low repair rate limit its industrial application. In this study, natural hematite was used as an auxiliary material for soil remediation in a bio-electrochemical system. It was found that the power density of soil microbial fuel cell (SMFC) system composed of 2.0 mm hematite was 2.889 mW/m2, which is 2.7 times compared with the blank group (1.068 mW/m2) in the particle size optimization experiment. A similarly increased power density (1.068 to 2.467 mW/m2) was observed when the hematite content changed from 0 to 20% in the concentration optimization experiment. Under 20% and 2.0-mm hematite condition, the phenol removal rate was closed to 99% after 7 days, which is 1.9-folds compared with blank control (53%). These results suggest that addition of hematite enhances soil porosity and conductivity, and increases the number of electron acceptors in soil. These findings inspire that this economic and abundant natural mineral is expected to be a potential auxiliary material in the field of soil organic pollutant purification, and expand the understanding of interactions between hematite and microorganisms in nature. [ABSTRACT FROM AUTHOR]

Rare earth elements (REEs) are considered environmental pollutants that have received extensive attention recently. The accumulation of REEs in plants is important because REEs can eventually enter the human body via the food chain. Marigolds are widely utilized as medicinal and commercial plants in medicine, feed, and therapeutics. Due to the extremely high demand for marigold in global, it is urgent to investigate the accumulation and distribution of REEs in marigold plants to reduce human and animal health risks. Marigold leaves tended to bioaccumulate the highest amounts of REEs from soil compared with other tissues. The distribution patterns of REEs in marigold were similar to those in the rhizosphere soil, which was enriched in light rare earth elements. Cerium accumulated most in marigold and soil, accounting for nearly 50% of ΣREEs, followed by lanthanum, neodymium, and yttrium. Roots were the most susceptible tissue affected by soil REE concentration, and a significant positive correlation was observed for REEs in the roots of marigold and soils (R = 0.87), while no significant correlation was observed for REEs in soils and other tissues. REEs were poorly transferred from soil to marigold, with bioaccumulation factor values for all tissues of marigold less than one. Additionally, REEs exhibited a positive correlation with Al and Fe in the roots, stems, leaves, and flowers of marigold. The present research revealed the biological interactions between marigold and soil and the distribution of REEs in various parts of marigold. It provides a reference for large-scale commercial cultivation and potential environmental risk in the future. [ABSTRACT FROM AUTHOR]

As a novel technique with a wide range of applications, microbial fuel cell (MFC) could simultaneously remove organic contaminants and heavy metals in complex wastewater, despite striking differences in physicochemical properties of these contaminant. But its wastewater treatment efficiency is restricted by its lower generation performance. However, approaches for the modification of MFCs' cathode with appropriate catalyst could effectively overcome this limitation. Herein, a new-type efficient cathode catalyst was invented through modifying natural molybdenite via one-step oxidation method. In this case, molybdenite had many changes in morphology (wave-shaped bending, fragmentation and decrescent diameter) during oxidation modification process, and oxidation-modified molybdenite could provide much more active sites for the cathode. After applying this novel cathode catalyst, the electric generation capacity of MFC system increased by 5.08 times, and its simultaneous degradation efficiency of methyl blue (MB) and Cr (VI) increased by 3.35 times (compared with graphite cathode MFC). This study provides a novel low-carbon and environmentally friendly way to prepare high efficiency cathode catalyst materials and provides a new idea of simultaneous purification for organic and metallic pollutants from complex wastewater. [ABSTRACT FROM AUTHOR]

The thermal performance of a heat pipe with axially trapezoidal grooves (HPATG) varies with inclination angles (the evaporator section is at lower position) under different heat loads is experimentally investigated in this paper. The inclination angles can be adjusted by a performance test system we built for this experiment. The axial temperature distribution of the HPATG under different working conditions (i.e., heat input as well as inclination angles) is obtained. The effects of heat loads and gravity caused by inclination on the thermal resistance as well as equivalent thermal conductivity of the HPATG are analyzed. Results indicate that the gravity exerts a vital effect on the axial temperature distribution of the HPATG under different heat loads. The heat transfer performance can be effectively enhanced under an appropriate inclination angle due to the well-matched relationship among the evaporation process of working liquid in grooves, condensation process of working medium and timely reflow of condensate liquid back to evaporator section. Additionally, the positive role of gravity on the evaporation heat transfer characteristics of HPATG becomes more obvious when the heat input keeps increasing. [ABSTRACT FROM AUTHOR]

An analog signal processing (ASP) circuit used for CMOS image sensor (CIS) readout is presented. The proposed ASP mainly includes a two-stage programmable gain amplifier (PGA), a sample-and-hold amplifier (SHA) merged by a pipelined analog–digital converter (ADC), and a digital-analog converter (DAC). Compared with conventional readout architecture, the proposed can provide finer gain, level shifting as well as offset calibrating function. A 1.5-Mpixel 60-fps CIS with the ASP is fabricated in a 0.13 μm 1P4M CMOS mixed signal process. The experiment results indicate the sensor can normally capture images without missing code. Moreover, the measured maximum gain error of the PGA is 1.6%, and the power dissipation is 16.5 mW for single ASP. [ABSTRACT FROM AUTHOR]

Efficient thermal management has become an important challenge for the integration and miniaturization of electronic devices with high power density. Phase change material (PCM)-based finned heat sink is an efficient passive cooling technology for an intermittent-use electronic device with high power density. The present work reports an experimental study on the transient thermal performance of PCM-based finned heat sinks for thermal management of electronic devices, with particular emphasis on the roles of heat load and PCM volumetric fraction. The temperature response and melting front evolution in heat sinks are analyzed and compared with the corresponding cavity. Moreover, the effects of heat load, fin geometry and PCM volumetric fraction on the melting performance of heat sinks are discussed. The results indicate the presence of fins effectively improves the thermal performance of PCM-based heat sinks, and a more fin number leads to a lower operating temperature and hence the duration of electronic devices is longer in an accepted temperature. Moreover, a higher input heat flux results in a higher operating temperature and a shorter duration of low operating temperature. The increase in PCM volumetric fraction enhances the thermal storage capacity of finned heat sinks and reduces the operating temperature. Therefore, the finned heat sinks filled with PCM ensure sufficiently low operating temperature for perfect reliability and duration of high-power-density electronic devices. [ABSTRACT FROM AUTHOR]

This paper presents a high-performance mixed controlled crystal oscillator. The digital-controlled part is based on a Pierce topology with switched-capacitor bank. Wide tuning range and high linearity are simultaneously achieved by combining discrete capacitors and a continuous voltage tuning varactor. The pull ability is around 99 ppm output frequency variation range. For noise reduction, the supply voltage of the mixed controlled crystal oscillator is regulated at 2.5 V by using on-chip low-drop regulators. The measured phase noise is −145 dBc/Hz at 1 kHz offset frequency by using a 40 MHz fundamental AT–cut crystal. The chip area is 3.6 mm2 for a 0.35 μm standard CMOS process with 3.3 V supply voltage and the power dissipation is 7 mW. [ABSTRACT FROM AUTHOR]

This paper describes a readout IC (ROIC), which consists of a capacitively coupled instrumentation amplifier (CCIA) and a discrete-time delta–sigma modulator. An active high-pass filter is embedded in the ripple reduction loop to suppress the noise ripple amplitude due to chop modulation. To accommodate the input with large electrode offset, dc-servo loop (DSL) and a 6 bit capacitive DAC are employed to suppress large electrode offset, while a positive feedback loop to boost its input impedance. The complete CCIA is implemented in a standard 0.18 μm 1P6M CMOS process. It occupies an area of 0.56 mm2 (including DSL) and consumes 52 μA current from a 3.3 V supply voltage. Measurement results indicate that the input reference noise PSD is 53.8 nV√Hz. [ABSTRACT FROM AUTHOR]

A theoretical model of unsteady melting heat transfer in a horizontal tube-shell TES unit is established and numerically solved based on the enthalpy-porosity method. In present research, the evolution of temperature field, velocity field, melting front and PCM enthalpy during the melting process under gravity and microgravity fields are compared and analyzed. The results indicate that the melting heat transfer under microgravity is dominated by heat conduction, while the natural convection dominates in the melting process under gravity. Consequently, melting performance under microgravity is weaker than that under gravity. Under gravity condition, vortices appear in the top half of the PCM and accelerate the melting process, and then the melting rate slows down gradually with the decrease of temperature gradient in PCM. However, due to no flow in the melting zone and the poor thermal conduction of PCM under microgravity, the melting area moves slowly outward in a circular type along the radial direction. In addition, the enthalpy difference of PCM under these two cases gradually enlarges as the melting goes on. At a typical time of 26,000 s, the enthalpy value of PCM under gravity is twice that under microgravity. [ABSTRACT FROM AUTHOR]

A flow-focusing microfluidic chip based on assembled capillary method is developed and the solid-core encapsulation behaviors of double emulsion in a flow-focusing microchannel are visually observed via high-speed microscopic imaging system. The experimental results identify the encapsulation of single, double and triple cores in a flow-focusing microchannel arising from the competition among the inertial force of inner phase, the shear force of outer phase fluid, and the interfacial tension. In addition, the solid-core encapsulation of double emulsion in flow-focusing microchannel is either in the stable state or in the transition state, depending on the flow rates of inner and outer phase fluid. The stable microencapsulation includes the stable single-core, double-cores and triple-cores encapsulation states, while the transition microencapsulation includes the single-double-cores and double-triple-cores transition encapsulation state. Irrespective of encapsulation state, the solid-core encapsulation process can be classified into four stages, including entering, neck stretch, neck shrinking and breakup. [ABSTRACT FROM AUTHOR]