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Water is a vital resource essential to the survival and development of all creatures. With the rapid growth of industry and agriculture, people face a severe threat of ecological destruction and environmental pollution while living earthly lives. Water pollution, in particular, harms people’s health the most. As a result, water supply security has become a top priority. As a critical point in water supply safety, monitoring water quality effectively and forecasting sudden water contamination on time has become a research hotspot worldwide. With the rapid development and wide applications of artificial intelligence and computer vision technologies, biological activity identification-based intelligent water quality monitoring methods have drawn widespread attention. They were taking fish activities as the water-quality indicator has gained extensive attention by introducing advanced computer vision and artificial intelligence technologies with low cost and ease of carrying. This article comprehensively reviews recent progress in the research and applications of machine vision-based intelligent water quality monitoring and early warning techniques based on fish activity behavior recognition. In detail, it addresses water quality-oriented fish detection and tracking, activity recognition, and abnormal behavior recognition-based intelligent water quality monitoring. It analyzes and compares the performance and their favorite application conditions. Finally, it summarizes and discusses the difficulties and hotspots of water quality monitoring based on the fish’s abnormal behavior recognition and their future development trends.

Hail, an intense convective catastrophic weather, is seriously hazardous to people’s lives and properties. This article proposes a multi-step cyclone hail weather recognition model, called long short-term memory (LSTM)-C3D, based on radar images, integrating attention mechanism and network voting optimization characteristics to achieve intelligent recognition and accurate classification of hailstorm weather based on long short-term memory networks. Based on radar echo data in the strong-echo region, LSTM-C3D can selectively fuse the long short-term time feature information of hail meteorological images and effectively focus on the significant features to achieve intelligent recognition of hail disaster weather. The meteorological scans of 11 Doppler weather radars deployed in various regions of the Hunan Province of China are used as the specific experimental and application objects for extensive validation and comparison experiments. The results show that the proposed method can realize the automatic extraction of radar reflectivity image features, and the accuracy of hail identification in the strong-echo region reaches 91.3%. It can also effectively realize the prediction of convective storm movement trends, laying the theoretical foundation for reducing the misjudgment of extreme disaster weather.

In view of the heat dissipation of electronic components with high heat flux, five phase change heat transfer cold plates with different structures and processing methods were designed, the effects of cold plate structural parameters, heat flux, refrigerant flow rate, and heat source layout on heat transfer performance, resistance of cold plate, and the pump power consumption were experimentally studied. The results show that the designed perforated cold plate has excellent heat transfer performance. The designed perforated cold plate maintains a temperature difference of less than 25 ℃ between the heat source surface and the refrigerant inside the cold plate when dissipating a total heat output of 5 000 W and a heat flux of 38 W/cm2, with cold plate resistance less than 30 kPa and pump power consumption less than 35 W. The processing method of cold plate has a significant influence on its heat transfer effect. The cold plate should adopt integrated design as far as possible to reduce the link of heat transfer and avoid the contact thermal resistance caused by the chimerism of different materials. When multiple heat sources have different heat flux densities, placing the higher heat flux heat source closer to the inlet of the cold plate achieves better heat transfer efficiency.

The miniaturization and performance improvement of components continuously increase the power of electronic devices. Superior heat-dissipation performance is important for the reliability of electronic devices. In this study, an experimental pump-driven refrigerant two-phase cold-plate-cooling system was developed. Four two-phase cold plates with different materials (Cu and Al) and channel heights (10 mm and 15 mm) were designed and processed. The heat-transfer performance of the cold plates, together with their flow resistance characteristics, pump power under different heat fluxes (4.4–22.2 W/cm2), refrigerant cooling capacities (3–11 kW), and heat source positions were studied. The results indicated that the heat-transfer performance of the two-phase cold plate was superior. The maximum heat transfer coefficient was 26 kW/(m2?℃) when dealing with a concentrated heat source with a heat dissipation of 1 000 W and a heat flux of 22.2 W/cm2. The temperature difference between the heat source surface and the refrigerant was less than 15 ℃ when the total pressure drop of the system was less than 20 kPa and the power consumption of the refrigerant pump was less than 20 W. A natural cold source can be used for heat dissipation to achieve energy savings. The heat transfer characteristics of the two-phase cold plate can be described by the fin efficiency correlation and the Kandlikar heat transfer correlation. The deviation between the temperature difference calculated by the theoretical formula and the measured value was less than 1 ℃. The results of this study can guide the design of cold-plate channels.

In this study, physical models of six-row and four-row arrays of a low-ambient-temperature air-source heat pump with and without wall obstruction are established. A three-dimensional numerical simulation of the ambient flow field of the low-ambient-temperature air-source heat pump under nominal working conditions at 261.15 K is carried out. In this study, the inlet air temperature of the evaporator surface and the heat transfer rate of the low-ambient-temperature air-source heat pump under different horizontal wind speeds are investigated. The location of the unit under the worst conditions is determined, and the influence of cold air backflow on the heat transfer performance is analyzed. The ambient wind hindered the diffusion of cold air at the fan outlet and increased the deflection angle of the fan outlet, resulting in the accumulation of cold air in the upper part of the fan, and the cold air reflux phenomenon in the unit was more obvious inside and on the lee side the array. The results showed that when the horizontal distance between the units was 0.6 m, the horizontal wind speed increased from 0 to 5 m/s. The lowest inlet air temperature of the array unit is 2.44–3.69 K lower than the ambient temperature; the average heat transfer decreases by 1%–6.2%, and the average inlet air temperature is 0.78–1.57 K lower than the ambient temperature. When the distance between the unit and wall is 0.6 m, the horizontal wind speed increases from 0 m/s to 5 m/s, respectively; the lowest inlet air temperature of the array unit is 3.51–4.14 K lower than the ambient temperature; the average heat transfer rate decreases by 5.9%–11.5%, and the average inlet air temperature is 1.29–1.98 K lower than the ambient temperature. On this basis, an array air-source heat pump was simulated under different lateral spacings and distances from the wall. The results showed that increasing the lateral spacing or distance from the wall enhanced the heat transfer of the array low-ambient-temperature air-source heat pump unit. When the lateral spacing increases to 1.8 m, the average heat transfer rate of the array unit can reach more than 96.5% of the baseline heat transfer rate of the array unit. When the distance from the wall is increased to 1.8 m, the average heat transfer rate of the array unit can be more than 91.3% that of the baseline unit. A horizontal spacing or a spacing from the wall of 1.2 m is a better installation spacing, which provides a theoretical basis for on-site installation.

In this study, a 294 L high-low temperature test chamber with two power batteries in the test area is investigated. The temperature rise and heat dissipation of the batteries in the chamber at a constant temperature of 45 ℃ are simulated through CFD, and the flow field of the high-low temperature test chamber is analyzed and optimized. The results show that for the air distribution pattern on the same side as the upper air supply and lower air return, the perforated plate in the upper part of the test area is helpful in improving the uniformity of the flow field. A vortex phenomenon occurs between the two power batteries. Increasing the distance between the shelf and bottom of the test chamber and appropriately increasing the return air grille area can reduce or even eliminate this phenomenon and thereby improve the flow field uniformity. When the distance between the shelf and bottom of the inner chamber increases to 0.2 m and the height of the return air grille increases to 0.15 m, the overall inhomogeneity of the flow field in the test chamber decreases from 1.73 to 0.4, and the vortex phenomenon between the batteries disappears.

The northern South China Sea continental margin is the key or critical segment of the Ocean-Continent Connection Zone (OCCZ) of the Great South China Block, the junction between the Tethyan and the (Paleo-) Pacific dynamic systems, and the interaction area between the Indian Ocean and the Pacific Ocean. However, due to the low-degree geophysical exploration in the past, the regional tectonic background, processes and mechanism of the transition between the Tethyan and the Pacific tectonic domains are unclear. Based on the latest large number of seismic profiles, we focus on the Cenozoic basin structure in the continental margin of the northern South China Sea and try to reveal the Mesozoic basement structures of the northern South China Sea continental margin, with the aim of exploring the pre-Cenozoic tectonic evolution and the Cenozoic opening, spreading, ridge fossil and closure of the South China Sea oceanic basin, so as to serve the accurate oil and gas exploration in this area at the same time. The seismic interpretation of the Pearl River Mouth Basin and the field structural investigation of the South China continental margin show that the OCCZ of the South China Block has experienced three processes: Mesozoic Indosinian collisional orogeny, Early Yanshanian accretionary orogeny and Late Yanshanian transpressive orogeny. During the Cenozoic era, it experienced the dispersive extension into basins under the control of NW-SE-directed normal extension in the early stage, the dextral pull-apart into basins under the control of NE-NNE-trending strike-slip faults in the middle stage, and the sinistral pull-apart into basins under the control of NW-WNW strike-slip faults in the late stage. In general, the transition process from the Tethyan to the Pacific tectonic systems can be subdivided into four stages: the transition from the Paleo-Tethyan to the Neo-Tethyan tectonic systems, the transition from the Neo-Tethyan to the Paleo-Pacific tectonic systems, the transition from the Neo-Tethyan to the Pacific tectonic systems, and the transition from the Paleo-Pacific to the Pacific tectonic systems. The tectonic transition of the East Asian OCCZ reflects the long-term mechanism of the Earth plate dynamic system driving the plate superconvergence in East Asia, in particular of the importance of the deep or submarine “Triple Poles”, the Southeast Asian U-shape subduction system, the Pacific LLSVP and the African LLSVP. More importantly, the Southeast Asian U-shape subduction system is also one of the important dynamic engines of the Earth plate motion.

[Introduction] The energy consumption of air conditioners is gradually increasing, which is one of the main reasons for the difference between the peak and valley power consumption of the power grid. Analyzing the characteristics of district cooling and cold storage technology and actively adjusting the distribution of electricity consumption of air conditioning and refrigeration systems to reduce the peak load of electricity consumption, provide references for planning, design, and operation of district cooling. [Method] Combining the literature review of cold storage engineering research and actual case analysis, we botained the characteristics of water storage and ice storage technology outside the coil, the nature of resources for district cooling and the principles to be followed. [Result] The results show that development of district cooling and cold storage technologies in China is promising. The water storage system is flexible and convenient, and it is advisable to use the electricity price mechanism to encourage users to invest themselves. As for the ice storage system outside the coil, the initial investment and total life cycle cost per unit of the cold storage system show a downward trend with the increase of the size of the cold storage system, but the change trend is gradually flattening. District cooling projects should be planned in advance. And it is regarded as a project that maximizes the benefit of resources of all members of the district. All members must participate to get the maximum benefit and share it with all members. [Conclusion] This work provides some guidance for further study on district cooling and cool storage technology.

In a mobile air conditioner with a double air duct, two nozzles were installed at the lower left and lower right corners of the condenser respectively, for spray cooling. With an enthalpy difference experiment, the temperature at different state points, energy consumption and refrigerating capacity were tested with outdoor temperatures of 35 ℃/24 ℃ and indoor temperatures of 27 ℃/19 ℃ (dry bulb temperature/ wet bulb temperature), and the influence of different spray quantities from 0.55 g/s to 2.10 g/s on the performance of mobile air conditioning was analyzed. The results show that with the increase in spray quantity, the evaporating pressure was almost unchanged at 1.0 MPa, but the condensing pressure decreased from 3.45 MPa to 3.14 MPa, and the condensing temperature decreased from 55.5 ℃to 51.3 ℃. Moreover, energy consumption decreased from 1582.95 W to 1465.1 W, refrigerating capacity increased from 3090 W to 3339 W, and the EER increased from 1.95 to 2.28. The cold exergy was small and the exergy efficiency of the system was only 5.19% to 6.08% because of a small difference of only 8 ℃ between the indoor and ambient temperatures. Among the different components, the maximum exergy loss coefficient occurred in the compressor, which was 0.496, 0.472, 0.479 and 0.476, respectively, while the lowest exergy efficiency was obtained in the evaporator, which was only 24.6%–26.0% .

To solve the problems involving insufficient liquid supply in the low-condensation temperature of the vapor compression air-conditioning refrigeration system and the low utilization rate of natural cold energy in the cold season, an air-conditioning system based on refrigerant pump boosting was designed, and the operating characteristics of the system was experimentally studied in this paper. The system can be operated in three modes: vapor compression, refrigerant pump boost, and single refrigerant pump drive in hot summer, transitional season, and cold winter. The results show that the traditional compression vapor refrigeration system using a capillary tube and an electronic expansion valve in the experiment suffers from insufficient liquid supply and reduced cooling capacity when the outdoor temperature is below 25 ℃and15 ℃, respectively. Furthermore, it can achieve a rated cooling capacity of more than 100% and a COP of 3.96 to 6.25 in the working conditions with an outdoor temperature of 25 ℃ to -5 ℃.This satisfies the operating requirements of the transition season. When the outdoor temperature is lower than -5 ℃, the use of a single refrigerant pump drive can satisfy the rated cooling capacity and exhibit a COP of more than 19.

Abstract SnO2 nanorod array grown directly on alloy substrate has been employed as the working electrode of H2O2 biosensor. Single-crystalline SnO2 nanorods provide not only low isoelectric point and enough void spaces for facile horseradish peroxidase (HRP) immobilization but also numerous conductive channels for electron transport to and from current collector; thus, leading to direct electrochemistry of HRP. The nanorod array-based biosensor demonstrates high H2O2 sensing performance in terms of excellent sensitivity (379 μA mM−1 cm−2), low detection limit (0.2 μM) and high selectivity with the apparent Michaelis–Menten constant estimated to be as small as 33.9 μM. Our work further demonstrates the advantages of ordered array architecture in electrochemical device application and sheds light on the construction of other high-performance enzymatic biosensors.

Abstract Carbon-coated SnO2 nanorod array directly grown on the substrate has been prepared by a two-step hydrothermal method for anode material of lithium-ion batteries (LIBs). The structural, morphological and electrochemical properties were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical measurement. When used as anodes for LIBs with high current density, as-obtained array reveals excellent cycling stability and rate capability. This straightforward approach can be extended to the synthesis of other carbon-coated metal oxides for application of LIBs.

OBJECTIVE: Generally, anterior lumbar interbody fusion (ALIF) was believed superior to transforaminal lumbar interbody fusion (TLIF) in induction of fusion. However, many studies have reported comparable results in lumbosacral fusion rate between the two approaches. This study aimed to evaluate the realistic lumbosacral arthrodesis rates following ALIF and TLIF in patients with degenerative spondylolisthesis as measured by CT and radiology. METHODS: Ninety-six patients who underwent single-level L5-S1 fusion through ALIF (n = 48) or TLIF (n = 48) for degenerative spondylolisthesis at the Spine Center, University of California San Francisco, between October 2014 and December 2017 were retrospectively evaluated. Fusion was independently evaluated and categorized as solid fusion, indeterminate fusion, or pseudarthroses by two radiologists using the modified Brantigan-Steffee-Fraser (mBSF) grade. Clinical data on sex, age, body mass index, Meyerding grade, smoking status, follow-up times, complications, and radiological parameters including disc height, disc angle, segmental lordosis, and overall lumbar lordosis were collected. The fusion results and clinical and radiographic data were statistically compared between the ALIF and TLIF groups by using t-test or chi-square test. RESULTS: The mean follow-up period was 37.5 (ranging from 24 to 51) months. Clear, solid radiographic fusions were higher in the ALIF group compared with the TLIF group at the last follow-up (75% vs 47.9%, p = 0.006). Indeterminate fusion occurred in 20.8% (10/48) of ALIF cases and in 43.8% (21/48) of TLIF cases (p = 0.028). Radiographic pseudarthrosis was not significantly different between the TLIF and ALIF groups (16.7% vs 8.3%; p = 0.677). In subgroup analysis of the patients without bone morphogenetic protein (BMP), the solid radiographic fusion rate was significantly higher in the ALIF group than that in the TLIF group (78.6% vs 45.5%; p = 0.037). There were no differences in sex, age, body mass index, Meyerding grade, smoking status, or follow-up time between the two groups (p > 0.05). The ALIF group had more improvement in disc height (7.8 mm vs 4.7 mm), disc angle (5.2° vs 1.5°), segmental lordosis (7.0° vs 2.5°), and overall lumbar lordosis (4.7° vs 0.7°) compared with the TLIF group (p  0.999). CONCLUSIONS: With a minimum 2-year radiographic analysis of arthrodesis at lumbosacral level by radiologists, the rate of solid radiographic fusions was higher in the ALIF group compared with the TLIF group, whereas the TLIF group had a higher rate of indeterminate fusion. Radiographic pseudarthrosis did not differ significantly between the TLIF and ALIF groups.

Abstract A novel octahedron-like hierarchical structure of Bi2WO6has been fabricated by a facile hydrothermal method in high quantity. XRD, SEM, TEM, and HRTEM were used to characterize the product. The results indicated that this kind of Bi2WO6crystals had an average size of ~4 μm, constructed by quasi-square single-crystal nanosheets assembled in a special fashion. The formation of octahedron-like hierarchical structure of Bi2WO6depended crucially on the pH value of the precursor suspensions. The photocatalytic activity of the hierarchical Bi2WO6structures toward RhB degradation under visible light was investigated, and it was found to be significantly better than that of the sample fabricated by SSR. The better photocatalytic property should be strongly associated with the high specific surface area and the abundant pore structure of the hierarchical octahedron-like Bi2WO6.

The experiment of quick freezer’s refrigeration system is carried out to study it’s cooling curve and refrigeration performance. The experimental results show that: when the refrigeration system of the quick freezer begins to cool down, the evaporation temperature is dropped immediately to be close to the lowest evaporation temperature and the evaporator’s inlet temperature has a difference with water’s temperature about 25 ℃; the lower evaporating temperature leads to the smaller mass flow rate of refrigerant entering the compressor, and compressor’s power accounts for only about 60% of the rated power; the exergy loss is about 41% in the evaporator, thus to make the evaporation temperature match with the indoor temperature of quick freezer is an important means to increase the freezer’s cooling speed sharply.

Study designRetrospective cohort study.ObjectiveOvercorrection in adult spinal deformity (ASD) surgery may lead to proximal junctional kyphosis (PJK) because of posterior spinal displacement. The aim of this paper is to determine if the L1 position relative to the gravity line (GL) is associated with PJK.MethodsASD patients fused from the lower thoracic spine to sacrum by 4 spine surgeons at our hospital were retrospectively studied. Lumbar-only and upper thoracic spine fusions were excluded. Spinopelvic parameters, the L1 plumb line (L1PL), L1 distance to the GL (L1-GL), and Roussouly type were measured.ResultsOne hundred fourteen patients met inclusion criteria (63 patients with PJK, 51 without). Mean age and follow up was 65.51 and 3.39 years, respectively. There was no difference between the PJK and the non-PJK groups in baseline demographics, pre-operative and immediate post-operative pelvic incidence-lumbar lordosis mismatch, sagittal vertical axis, or coronal Cobb. The immediate postoperative L1-GL was -7.24 cm in PJK and -3.45 cm in non-PJK (P < 0.001), L1PL was 1.71 cm in PJK and 3.07 cm in non-PJK (P = 0.004), and PT (23.76° vs 18.90°, P = 0.026) and TK (40.56° vs 31.39°, P < 0.001) were larger in PJK than in non-PJK. After univariate and multivariate analyses, immediate postoperative TK and immediate postoperative L1-GL were independent risk factors for PJK without collinearity.ConclusionsA dorsally displaced L1 relative to the GL was associated with an increased risk of PJK after ASD surgery. The postoperative L1-GL distance may be a factor to consider during ASD surgery.

Single and double row parallel-flow condensers had been used in the refrigerated display cabinet. This system was compared to the refrigerator system which used fin-and-tube condenser. This study show that the compressor average power consumption in a cycle was minimum when refrigerant was charged 550g, 650g and 800g respectively in the refrigerator systems which used single, double row parallel-flow and fin-and-tube condensers. The system with double row parallel-flow condenser consumed the least power among the three systems, and the system with single row parallel-flow condenser was almost the same with the system with fin-and-tube condenser. In the air side, parallel-flow condensers’ performance was better than the fin-and-tube condenser. The single and double row parallel-flow condensers only have a quarter and a half volume of the fin-and-tube condenser in the experiment, which indicates that parallel-flow condenser will be a good solution for the insufficient heat exchange capacity in the harsh environment and reduction of the cost when applied in refrigerator.