Series Connection Research Articles

Evidence of serial connection between the plasma volume and two interstitial fluid compartments

BackgroundKinetic analysis of fluid volume shifts can identify two interstitial fluid compartments with different turnover rates, but how they are connected to the bloodstream is unknown. MethodsRetrospective data were retrieved from 217 experiments where 1.5 L of Ringer's solution (mean) had been administered by intravenous infusion over 30 min to awake and anesthetized humans (mean age 40 years). Urinary excretion and hemoglobin-derived plasma dilution served as input variables in a volume kinetic analysis using mixed models software. Possible modes of connection between the two interstitial fluid compartments and the bloodstream were judged by covariance analysis between kinetic rate constants, physiological variables, and time factors. ResultsThe return flow of already distributed fluid to the plasma via a fast-exchange interstitial compartment was inhibited ongoing infusion of fluid (−38 %), which was probably due to increase of the venous pressure during volume loading. Ongoing infusion also greatly retarded the entrance of fluid to the slow-exchange compartment (−85 %), which suggests that infused Ringer's first had to enter the fast-exchange compartment. A high mean arterial pressure markedly increased the urine output and, to a lesser degree, also the rate of entrance of fluid to the fast-exchange compartment. Moreover, a high blood hemoglobin concentration retarded the rate of entrance of fluid to the fast-exchange compartment. ConclusionsThe fast-exchange but not the slow-exchange interstitial fluid compartment was affected by intravascular events, which suggests that only the fast-exchange compartment is directly connected to the circulating blood.

Photoinduced Mechanical Cloaking of Diarylethene-Crosslinked Microgels.

The serial connection of multiple stimuli-responses in polymer architectures enables the logically conjunctive gating of functional material processes on demand. Here, a photoswitchable diarylethene (DAE) acts as a crosslinker in poly(N-vinylcaprolactam) microgels and allows the light-induced shift of the volume phase-transition temperature (VPTT). While swollen microgels below the VPTT are susceptible to force and undergo breakage-aggregation processes, collapsed microgels above the VPTT stay intact in mechanical fields induced by ultrasonication. Within a VPTT shift regime, photoswitching of the DAE transfers microgels from the swollen to the collapsed state and thereby gates their response to force as demonstrated by the light-gated activation of an embedded fluorogenic mechanophore. This photoinduced mechanical cloaking system operates on the polymer topology level and is thereby principally universally applicable.

15-kV/50-A SiC AC Switch Based on Series Connection of 1.7-kV MOSFETs

15-kV/50-A SiC AC Switch Based on Series Connection of 1.7-kV MOSFETs

An Enduring Na-Ion Solar Battery Configured with Na2Co0.5Ni0.5Fe(CN)6 Positive and NaTi2(PO4)3 Negative Electrodes in Na2SO4-SiO2 Hydrogel Electrolyte

A successful solar energy storage is accomplished in a 5 V/5 mAh rated Na-ion battery, which is customized by series connection of three 1.8 V unit cells. The unit cell is constructed with open framework structured Na2Co0.5Ni0.5Fe(CN)6 positive and Natrium Super Ionic CONductor (NaSICON) type NaTi2(PO4)3 negative electrodes in 1 M Na2SO4-SiO2 hydrogel electrolyte. Both positive and negative active materials demonstrate Faradaic charge storage mechanism with appreciable diffusion coefficients, such as 5.17 × 10−15 and 1.13 10−15, respectively. The Na2Co0.5Ni0.5Fe(CN)6//NaTi2(PO4)3 full cell depicts a specific capacity of 48 mAh g−1 (@ 100 mA g−1), an energy density of 95.68 Wh kg−1 (@ 259.96 W kg−1) and a power density of 779.75 W kg−1 (@ 54.36 Wh kg−1). The cell also exhibits an excellent durability, i.e., 93% capacity retention with 99% Columbic efficiency at 200 mA g−1 upon 1000 cycles. However, the 5 V battery is performance tested under solar-charging cum constant-load-discharging experiment for one-month, and the device describes 85% capacity retention over the period. The good power capability and cycle life with moderate energy density make this battery chemistry suitable for solar energy storage applications.

Investigation of Feature Engineering Methods for Domain-Knowledge-Assisted Bearing Fault Diagnosis.

The engineering challenge of rolling bearing condition monitoring has led to a large number of method developments over the past few years. Most commonly, vibration measurement data are used for fault diagnosis using machine learning algorithms. In current research, purely data-driven deep learning methods are becoming increasingly popular, aiming for accurate predictions of bearing faults without requiring bearing-specific domain knowledge. Opposing this trend in popularity, the present paper takes a more traditional approach, incorporating domain knowledge by evaluating a variety of feature engineering methods in combination with a random forest classifier. For a comprehensive feature engineering study, a total of 42 mathematical feature formulas are combined with the preprocessing methods of envelope analysis, empirical mode decomposition, wavelet transforms, and frequency band separations. While each single processing method and feature formula is known from the literature, the presented paper contributes to the body of knowledge by investigating novel series connections of processing methods and feature formulas. Using the CWRU bearing fault data for performance evaluation, feature calculation based on the processing method of frequency band separation leads to particularly high prediction accuracies, while at the same time being very efficient in terms of low computational effort. Additionally, in comparison with deep learning approaches, the proposed feature engineering method provides excellent accuracies and enables explainability.

Scaling up 3D-printed urine microbial fuel cells with the membrane electrode assembly

Urine microbial fuel cells (MFCs) show potential for urine treatment to achieve simultaneous organic matter removal and electricity production. However, factors affecting the performance of urine MFCs during scaling up remain unclear. This study develops a 3D-printed air-cathode urine MFC with the membrane electrode assembly (MEA). After scale-up in parallel, unstable anode potential is responsible for the open circuit voltage (OCV) difference among various units, which leads to the energy loss in the system. For systems connected in series, unstable cathode potential mainly contributes to the voltage reversal, resulting in large power loss. Electrochemical impedance spectroscopy analysis indicates dramatically increased ohmic and polarization resistance in both serial and parallel systems. Bode plot further demonstrates after parallel connection, an obvious capacitance effect is observed, which provides evidence to illustrate the phenomenon of non-Faradaic current. Compared to serially connected systems, the capacitor of power management system can harvest more energy from systems connected in parallel. The microbial community analysis demonstrates Geobacter is the most dominant anodic electroactive bacteria both before and after scale-up. Overall, these results show the different strategic improvement should be executed while utilizing parallel connection (focusing on anode) or serial connection (focusing on cathode) to scale up urine MFCs.

Harvesting and mapping ultrasonic vibration power using semiconducting wire-based tribovoltaic generators

Ultrasonic vibration is an excellent mechanical power source owing to its large power density. Harvesting ultrasonic vibrations has been demonstrated so far through piezoelectric effect, triboelectric effect, and electromagnetic induction. However, the majority of these devices only produce AC output which limits their potential applications. This work demonstrates, for the first time, the conversion of ultrasonic vibration power to DC output using semiconducting wire-based electric generators, in which one or several semiconductor wire/metal junction(s) are employed. A current density of up to 19 µA/cm2 and a peak power density of 5 µW/cm2 can be obtained under ultrasonic vibrations up to 37 kHz. The mapping of the ultrasonic vibrational strength has been achieved, demonstrating the capability of a self-driven powered ultrasonic sensor. The characteristics of individual semiconductor junctions and the series connection of several such junctions are studied using equivalent circuits.

Development and test: Future-proof substation designs for the low-temperature operation of domestic hot water systems with a circulation loop

On the transition toward low-temperature district heating (DH), generation sectors, distribution networks, and building consumers should all be adapted to low-temperature operation conditions. However, a bottleneck in lowering DH return temperatures is the domestic hot water (DHW) system with a circulation loop in multifamily buildings. Existing systems with a single heat exchanger often led to elevated return temperatures because of the reheating of the circulation loop. This study developed several innovative designs for future-proof DHW substations that decouple the heating of cold water and circulation flows, ensuring lower DH return temperatures in large multifamily buildings. First, a theoretical analysis was performed for benchmarking the return temperature for various proposed design configurations under low-temperature operation conditions; then, the proposed configurations were tested for a Danish multifamily building connected to a medium–low-temperature DH network. In the field tests, compared to a typical DHW substation with a single heat exchanger, the proposed configuration with the circulation loss booster reduced the average DH return temperature from 46.4 °C to 34.1 °C and 27.9 °C for parallel or serial connections, respectively. Economic analysis confirms the viability of the proposed solution, with a payback period ranging from 3.4 to 7.9 years.

Experimental and numerical analysis of oily wastewater treatment using low-cost mineral adsorbent in a single and multi-fixed bed column

In this research, single and multi-bed adsorption columns for oily wastewater treatment were investigated both experimentally and numerically. For this purpose, two mineral adsorbents, namely natural zeolite and calcined bentonite, were used. The adsorbent characteristics were analyzed by XRD, BET, and SEM. Adsorption isotherm and single fixed-bed adsorption column performance for both adsorbents were experimentally assessed at different concentrations. In addition, single- and multi-fixed-bed column applicability with two different configurations, series and parallel connections, were simulated. The experimental results showed that Freundlich and Langmuir isotherms had the best performance to describe the adsorption of calcined bentonite and natural zeolite, respectively. Moreover, natural zeolite has better performance for oily wastewater treatment than calcined bentonite. The maximum capacity of calcined bentonite and natural zeolite was obtained at 3.06 mg/g and 5.37 mg/g, respectively. The simulation results indicated that the maximum separation yields of single fixed-bed, multi-fixed-bed with series connections, and multi-fixed-bed with parallel connections were 39.3%, 99.98% and 74.58%, respectively. Adsorbent mass optimization indicated that the required adsorbent mass decreased by 33.1% when four beds were presented in an operation instead of a single bed. This research recommends a promising application of natural zeolite as an economic adsorbent in multi-bed adsorbers for oily wastewater treatment.

A High-Gain DC-DC Converter with a Wide Range of Output Voltage

In fuel-cell-powered electric vehicles, the output characteristics of the fuel cell are relatively soft, and the output voltage is unstable. Therefore, a DC-DC converter is required between the fuel cell and the inverter to transform the output voltage of the fuel cell into a suitable voltage for the motor drive. Existing non-isolated DC-DC converters cannot meet the requirements of high voltage gain, high efficiency and a wide range of output voltage simultaneously. To improve these performances, a high-gain DC-DC converter with a wide range of output voltage, based on a switched capacitor structure, is proposed in this paper. The converter supplies power to the load by connecting multiple capacitors with the input source in series in switch-on states, while the input source charges the capacitors through a series connection with an inductor in switch-off states. In comparison to existing converters, the proposed converter maintains high voltage gain at lower duty ratios and offers a wide range of output voltage. The operating principles, key waveforms and parameter design of the topology in Continuous Conduction Mode (CCM) are described and analyzed in detail, and the voltage gain of the proposed converter is compared with some other DC-DC converters. Finally, the results of simulations using Simulink and hardware experiments that were conducted to validate the theoretical analysis are described.

基于改进注意力机制的番茄叶部病害检测方法研究

The precise detection and recognition are the premise in accurate prevention and control of tomato diseases. To improve the accuracy of tomato diseases recognition model, nine kinds of sick leaves images including tomato target spot bacteria in Plant Village and healthy leaves images were used. A new attention mechanism module called CBAM-Ⅱ was created by changing the serial connection between Channel and Spatial attentions of CBAM to parallel connection, and then the results of two modules were added together. CBAM-Ⅱ had been verified to be effective and universal in the convolutional neural network model. The accuracy of MobileNet-V2 with CBAM-Ⅱ model was 99.47%，which had increased by 1.13%, 0.93%, 0.7%8 and 1.06 % respectively comparing with MobileNet-V2 model, MobileNet-V2 plus Channel attention module, MobileNet-V2 plus Spatial attention module, and CBAM attention module. Furthermore, the accuracy of AlexNet, Inception-V3 and ResNet50 model has increased 1.73, 0.15 and 0.33 % respectively when the CBAM-Ⅱ module was added. Results showed that the proposed module CBAM-Ⅱ created in this experiment is more effective in MobileNet-V2 model for tomato diseases recognition, and could solve interference problems resulted from the serial connection. Additionally, the accuracy of four convolutional neural network models including Mobilenet-V2, AlexNet, Inception-V3 and ResNet50 model had all increased when the CBAM-Ⅱ module was added, which represented the good universality of CBAM-Ⅱ module. The results could provide technical support in accurate detection and control of tomato diseases.

Multinuclear Pd(II) oligomeric nanohoop complexes with 2,2′‐bipyridyl‐embedded cycloparaphenylenes ligands exhibiting ultrahigh third‐order nonlinear optical performance

AbstractUnlike traditionally available linear frameworks, cyclic transition‐metal architectures with cycloparaphenylenes (CPPs) ligands provide new access to develop modern nonlinear optical (NLO) materials. In this work, a sequence of “staircase” Pd(II) oligomeric nanohoop complexes with the 2,2′‐bipyridyl‐embedded CPPs ligand unit through “series connection” mode and “Ω‐type” Pd(II) trimeric isomer have been systematically designed and investigated via density functional theory. Herein, we first report the dependence of third‐order NLO responses on the number of bipyridine CPP building ligands in a quantitative way. Impressively, the Pd(II) trimeric complexes possess ultrahigh third‐order NLO responses, which are ascribed to the large orbital delocalization and decreased energy gap. To our delight, the enlargement of the nanohoop size is beneficial to improving third‐order NLO responses for Pd(II) oligomeric nanohoop complexes, and the maximum absorption spikes show the blue shift tendency. The effect of size on the third‐order NLO responses becomes much larger with the addition of bipyridine CPPs ligand. Overall, we hope the current work will deliver a new quantitative structure–property relationship toward the design and synthesis of Pd(II) oligomeric nanohoop complexes with high third‐order NLO responses.

Heating Performance and Economic Analysis of Solar-Assisted Cold-Water Phase-Change-Energy Heat Pump System in Series and Parallel Connections

To study the heating performance of a solar-assisted cold-water phase-change-energy heat pump system, its heating performance under series and parallel connections is simulated for a community in Harbin, the influence of ice thickness on the different operation modes is analyzed, and the economy of the system is calculated for series and parallel connections in this paper. The results show that the water supply temperature is higher and more uniform in the parallel operation, and more terminal heat is supplied; the ice thickness has more of an influence on the series connection compared to the parallel connection; and the dynamic payback period is 6.72 years for the series connection and 7.28 years for the parallel connection. This case study can serve as a guide for practical engineering application projects and act as a reference for heating and economic data for the promotion of this heat pump system.

Performance evaluation of three constructed wetland-microbial fuel cell systems: wastewater treatment efficiency and electricity generation potential.

Constructed wetlands (CWs) have proven to be effective and environmentally friendly for removing pollutants, while microbial fuel cells (MFCs) offer the potential for electricity generation. Thus, this study evaluated the performance of three CW-MFC systems (zigzag, single-column, and triple-column continuous) for domestic wastewater treatment and electricity generation. Results showed that parallel connection of CW-MFCs significantly improved power generation compared to series connection. Additionally, using three copper wires to connect carbon fiber felt electrodes demonstrated superior pollutant capture capabilities compared to a single copper wire. During the 14-day testing period, the single-column system achieved the highest power density of 5.55 mW m-2, followed closely by the triple-column continuous system at 4.77 mW m-2. In contrast, the zigzag system exhibited a lower power density of 2.49 mW m-2. Interestingly, the implementation of facultative anaerobic conditions in the anode, along with the application of a plastic bag cover, facilitated the maintenance of anaerobic conditions in both the single-column and triple-column continuous systems. This resulted in increased power density and reduced internal resistance. In contrast, the zigzag system, with its larger surface area, aeration, and circulation, exhibited higher internal resistance and lower current dissipation. Despite its inferior electricity generation performance, the zigzag system demonstrated higher efficiency removal of chemical oxygen demand (COD), nitrate (NO3-), and phosphate (PO43-) than the single-column system. This can be attributed to the extended contact time, resulting in enhanced pollutant removal. Overall, the multi-column continuous system shows promise as a viable approach for simultaneous domestic wastewater treatment and electricity production, offering potential benefits for sustainable wastewater management.

Experimental Investigation on the Flow Boiling of Two Microchannel Heat Sinks Connected in Parallel and Series for Cooling of Multiple Heat Sources.

Cooling methods for multiple heat sources with high heat flux have rarely been reported, but such situations threaten the stable operation of electronic devices. Therefore, in this paper, the use of two microchannel heat sinks is proposed, with and without grooves, labeled Type A and Type B, respectively. Experimental investigations on the flow boiling of two microchannel heat sinks connected in parallel and in series are carried out under different mass fluxes. In addition, a high-speed camera is used to observe flow patterns in the microchannels. The cold plate wall temperature (Tw), heat transfer coefficient (HTC), and pressure drop (PD) are obtained with the use of two microchannel heat sinks. The flow patterns of the bubbly flow and elongated bubbles in the microchannels are observed. The results of the analysis indicated that the Tw, HTC, and PD of the two microchannel heat sinks connected in parallel were degraded, especially when using the Type A-B parallel connection. Compared to the use of a single heat sink, the maximum decrease in HTC was 9.44 kW/(m2K) for Type A heat sinks connected in parallel, which represents a decrease of 45.95%. The influence of the series connection on the Tw, HTC, and PD of the two heat sinks is obvious. The Type A-A series connection exerted the greatest positive effect on the performance of the two heat sinks, especially in the case of the postposition heat sink. The maximum increase in HTC was 12.77 kW/(m2K) for the postposition Type A heat sink, representing an increase of 72.88%. These results could provide a reference for a two-phase flow-cooling complex for multiple heat sources with high heat flux.

Extensive Analysis of a Reinvigorated Solar Water Heating System Using Low-Density Polyethylene Glazing

Solar energy is one of the most promising forms of alternative energy because it has no adverse effects on the environment and is entirely free. Converting solar energy into thermal energy is the most common and straightforward method; the efficiency of solar thermal conversion is approximately 70 percent. The intermittent nature of solar energy availability affects the performance of solar water heaters (SWH), which lowers the usefulness of solar energy in residential and commercial settings, particularly for water heating. Even at low temperatures, the performance of a collector can be improved by using low-density polyethylene (LDPE) glazing instead of traditional glass because it is less expensive and lighter than glass. Using a comprehensive experimental-simulative study, the Glass Solar water heater (glass SWH) and the low-density polyethylene solar water heater (LDPE SWH) are analyzed, examined, and compared in this work. These solar water heaters have galvanized iron (GI) as their absorber material. The SWHs were operated in a closed loop at a constant mass flow rate of 0.013 kg/s, and a 4E analysis (which stands for energy, exergy, economics, and efficiency recovery ratio) was carried out. This analysis included a look at the dynamic time, uncertainty, weight reduction, carbon footprint, and series connection. An LDPE SWH has an energy efficiency that is 5.57% and an exergy efficiency that is 3.2% higher than a glass SWH. The weight of the LDPE SWH is 32.56% lower than that of the glass SWH. Compared to the price of a conventional geyser, installing our SWH results in a cost savings of 40.9%, and monthly energy costs are reduced by an average of 25.5%. Compared to October, September has the quickest dynamic time to reach the desired temperature, while October has the most significant dynamic time. The efficiency recovery ratio (ERR) of a glass SWH is 0.0239% lower than that of an LDPE SWH. LDPE SWHs had a carbon credit worth INR 294.44 more than glass SWHs. The findings of these tests demonstrate that the LDPE SWH is a practical replacement for traditional means of heating water, such as SWHs and geysers.

Sodium alginate based energy harvesting fibers: Multiscale structure and moist-electrical properties

Moist-electric generation, a new energy harvesting technology, exhibits unique advantages in sustainable energy collection and compatibility with environment. However, the lack of research on fiber based moist-electric generation materials and multiscale structure-moist electric performance relationship has restrained the extensive development and application of this energy generation method. In this work, sodium alginate (SA)/multi-walled carbon nanotubes (MWCNT) coaxial fibers with radial gradient difference of oxygen-functional group are prepared through wet spinning. Meanwhile, the aggregate structures of SA/MWCNT fibers are regulated by adjusting the spinning and post-drawing process. The relation between moist electric generation performance and multiscale structure of SA/MWCNT fibers, including the effect of oxygenated group distribution and crystalline structure, are investigated for the clarification of moist-electric mechanism. Based on structure design, the coaxial fiber moist-electric generator (CFMEG) shows excellent moist-electric properties, continuous output ability, and environmental adaptability. The maximum output power density of CFMEG with a length of only 1 cm can reach 3.09 ∼ 9.50 μW/cm2 at RH = 90 ∼ 95% from an extreme voltage of 0.35 ∼ 0.38 V and current of 1.64 ∼ 1.74 μA, which exceeds most of the same type of moist-electric research. A long-last output voltage of 0.15 V for more than 36 h can be obtained from this CFMEG, which is able to generate an output voltage of 1.0 to 6.9 V after series and parallel connection to illuminate LEDs directly without additional capacitors. The CFMEG from multiscale structure design provides a way of preparation of flexible power supply devices using green resource with low density and exhibits great opportunity for common purpose application.

Profile of Student’s Mathematical Connection in Arithmetic Sequences and Series Based on Learning Styles

Profile of Student’s Mathematical Connection in Arithmetic Sequences and Series Based on Learning Styles

Dual-responsive epoxy thermosets with controlled degradation and high performance based on serial connection of double dynamic bonds

Covalent adaptable networks relying on dynamic cross-links have been developed to make the conventional thermosets degradable and reprocessable, but the greater challenge lies in how to overcome the trade-off between excellent degradability and mechanical properties. It remains a formidable challenge to achieve complete degradation of high mechanical materials (such as epoxy) especially at more moderate conditions. Herein, dual-responsive epoxy thermosets that were serially cross-linked by double dynamic bonds of disulfide bonds and cation-π interactions were prepared from diglycidyl ether of bisphenol A (DGEBA), dithiodianiline (DTDA), N-expoxypropane-indole (EIN) and MgCl2. The dual-responsive epoxy exhibited moderate mechanical properties with the tensile strength of 55 MPa, while the glass transition temperature (Tg) was 85 °C. In addition, the dual-responsive epoxy could be degraded by either DTT or PPi, due to the thiol-disulfide oxidation/reduction reaction and the complexation reaction of PPi and Mg2+. Furthermore, the degradation times could be controlled from <100 to 2700 min with optimal conditions by varying the concentration of reactive molecules and temperature. Meanwhile, the dual-responsive epoxy also exhibited excellent reprocessing properties. The dual-responsive dynamic epoxy thermoset is expected to be useful for coatings, adhesives, and matrix polymers of composites that require controlled degradation and recyclability.

Design and simulation study on the heating performance of mesh heating elements

AbstractTo achieve uniform heating of heat‐not‐burn cigarettes, the ANSYS Workbench was used to verify the calculation rule of the resistance value of the mesh heating element. To provide a theoretical basis for improving the design of mesh heating elements, the effect of rounded corners on the resistance value and that of key parameters such as the number of mesh heat emitters in series and parallel, mesh density, and heating power on the heating uniformity were investigated. The deviation of all calculation results is less than 2.4%, indicating that the total resistance value of the mesh heating element conforms to the calculation rule of the series and parallel connections of single‐module resistors. The heating power increases by 3.2%, which has a relatively small impact on the overall heating element when a rounded corner with a radius equal to the line width is added to the corner of the heating element. The area of the heating body increases when increasing the number of series connections and reducing the number of parallel connections, which is conducive to uniform heating. While maintaining the ratio of the number of series connections to the number of parallel connections constant, reducing the module size will not change the area of the mesh heating element, but it will improve the temperature uniformity. Under different power conditions, the heating uniformity of the same heating element does not change.