Optimum Volume Ratio Research Articles

Synthesis of Silver Nanoparticles with <i>Syzygium aromaticum</i> Leaves Extract as Antioxidant and Antimicrobial Materials

Silver nanoparticles (AgNPs) have attracted attention due to their unique properties and potential application. This research aimed to do green synthesis of AgNPs with Syzygium aromaticum leaves extract (SALE) and evaluate their antibacterial and antioxidant activities. Syzygium aromaticum leaves were extracted using distilled water at 70 °C for 30 min and the results were characterized with FTIR. AgNPs were synthesized by mixing AgNO3 precursor with SALE. The effects of parameters such as volume ratio of AgNO3 precursor to SALE, AgNO3 concentrations, and synthesis times were investigated. The synthesized AgNPs were characterized using UV-Vis spectrophotometer, FTIR, and TEM. Antibacterial activity of SALE and AgNPs was investigated against Escherichia coli (E.coli) and Bacillus subtilis (B. subtilis) with disc diffusion method and antioxidant activity was tested with DPPH method. The FTIR characterization revealed that SALE and resulting AgNPs contain O-H, C-H, C=O, C=C, C-O, and C≡C functional groups. The UV-Vis characterization demonstrated that AgNPs exhibited an absorption peak at λ = 420 nm indicating surface plasmon resonance. The optimal volume ratio of AgNO3 to SALE, AgNO3 concentrations, and synthesis time for AgNPs synthesis was achieved at 10:3, 5 mM, and 60 min respectively. TEM characterization indicated that AgNPs have spherical form and sizes ranging from 14 to 32 nm. The antibacterial testing revealed that AgNPs have antibacterial activities against E. coli and B. subtilis with inhibition zone values are 8,38 ± 0,48 and 6,88 ± 1,47 respectively. Additionally, antioxidant testing presented that the IC50 values were 85.05 µg/mL for SALE and 34.71 µg/mL for AgNPs. The results indicate that green synthesis of AgNPs from AgNO3 precursor with SALE was done successfully and this nanoparticle has good antibacterial and antioxidant activities.

A novel heat recovery VRF system: Principle and cooling performance analysis

Faced with an increasingly severe energy problem and increased demand for indoor comfort, heat recovery VRF systems have demonstrated remarkable potential for energy conservation. However, traditional heat recovery VRF systems need more suboptimal energy efficiency in terms of cooling and dehumidification and fail to guarantee precise temperature and humidity control in specific environments. In this study, a novel heat recovery VRF system that can achieve highly efficient cooling while ensuring precise humidity control is proposed. It can realize four primary operation modes by changing the function of indoor heat exchangers. The results showed that the optimal volume ratio of the two compressor cylinders was 1.4, which was used as the design parameter for the system. Compared to the single-evaporation temperature system, the proposed double-evaporation temperature system has better energy efficiency and dehumidification capacity in the cooling mode. The cooling coefficient of performance (COP) can be increased by 3.18 %–6.05 %, the compressor energy consumption can be reduced by 3.07 %–7.03 %, and the moisture extraction rate and latent heat ratio of the system can be increased by 5.6 %–33.3 %.

Study on optimization of preparation and liquid content of thermo-responsive inhibitor for preventing coal spontaneous combustion

To address the issue of fast failure of salt inhibiting liquid in preventing coal spontaneous combustion, our team proposed the use of a thermo-responsive secundina sphere inhibitor (TRSSI). This agent involved wrapping the salt inhibiting liquid with phase change materials (PCMs). The previous experimental results were proven. However, subsequent observations revealed surface cracks in the TRSSI upon room temperature cooling, leading to internal liquid leakage and a low rate of complete formation. To address this, this paper conducted a thermal analysis of the TRSSI preparation process. Through range analysis, three factors affecting the thickness of the shell were determined: notably, the ice-ball radius exhibited a significant positive correlation, while the initial temperature of the PA-SA had a substantial negative impact. Conversely, the initial temperature of the ice-ball showed relatively minimal influence on thickness. By combining the regression analysis equation and mechanical conditions, the optimal volume ratio, ice-ball radius, and shell thickness under varying compressive strengths were obtained. Water retention tests showed that the TRSSI exhibited a mere 3.67% water loss rate over nine months at room temperature. The adiabatic heating test of coal demonstrated that the TRSSI, when applied to coal seam surface, accurately targeted the heat source center and swiftly reduced its temperature. Ineffective TRSSIs absorbed heat, stacked on each other, and formed a tight water-retaining layer on coal seam surface, effectively prolonging the coal’s self-heating oxidation period.

Detonability of Ammonium Nitrate Mixtures with the Addition of Organic Materials

As an oxygen carrier and a strong oxidising agent, ammonium nitrate can create an explosive mixture when mixed with organic material. A typical example is the mixture of ammonium nitrate and fuel oil (ANFO), which is the most used explosive for civilian applications. In this work, we studied the detonability and detonation properties of mixtures of ammonium nitrate with recycled rubber and hay. The main goal of this study was to determine the optimal volume ratio of ammonium nitrate and organic materials in terms of achieving the best performance (working capacity). Using small experiments, it was determined that the maximum burst velocity for the ammonium nitrate/hay mixture is achieved at 8% hay by volume, while the maximum burst velocity for the ammonium nitrate/rubber mixture is achieved at 15% rubber by volume. A thermochemical calculation has shown that the maximum detonation heat is achieved at the zero oxygen balance at the volume ratios of 89.2/10.8 for AN/Rubber and 72.85/27.15 for AN/Hay.

Performance evaluation of gamma-type Stirling engine using combined Schmidt and mechanical loss model

This paper focuses on the study of gamma-type Stirling engine prototype using a combined Schmidt closed-form and mechanical loss analysis. Not restricted to optimizing the indicated power as classic Schmidt theory is set to, this analysis allows to maximize the shaft power due to the mechanical loss in power transmission. For this purpose, MATLAB code was developed to calculate the indicated and the shaft powers of the engine at different operating parameters. The results showed that shaft power peaks at swept volume ratios smaller than those of indicated power at different values of mechanism effectiveness. Within the range of engine mechanism effectiveness typically between 0.7 and 0.9, it was found that maximum shaft power for this particular engine can be achieved at different optimum values of swept volume ratio between 0.75 and 0.95 and phase angle between 80° and 90°. However, an optimum swept volume ratio was found to be <i>k</i>=0.55 of the same engine size for different scenarios of operation. Also, the developed model can be used as a design tool in the preliminary stage to find the optimum geometry of the engine. The new engine design parameters including the stroke, the crank radius and power piston bore, and engine alteration were presented.

The enhanced properties of amplified spontaneous emission and organic light emitting diodes based on Ag NPs doped hole transfer layer

The organic semiconductor lasers (OSLs) have been seen as a promising light source for future applications. Lower amplified spontaneous emission (ASE) threshold of the organic gain medium and optimized device structures are key factors to realize electrically pumped OSLs. In this paper, the silver nanoparticles (Ag NPs) doped PEDOT: PSS buffer layer was used to improve the ASE performance of BUBD-1 molecule and the optoelectronic performance of the corresponding organic light-emitting diodes (OLEDs). Compared with the reference device with pure PEDOT: PSS buffer layer, the lowest ASE threshold was obtained in CBP: 45 wt%BUBD-1 blend film at the optimal volume ratio 1:3 of PEDOT: PSS: Ag NPs, decreased by 6 times. Then the Ag NPs doped PEDOT: PSS buffer layer was used as both buffer layer and the hole transport layer in the OLEDs devices with CBP: 45 wt% BUBD-1 blend films as the emission layer. At the optimal volume ratio of PEDOT: PSS to Ag NPs, the maximum brightness increased more than 2 times to 7823 cd/m2, and the maximum EQE increased nearly 2 times to 2.81%. The improved ASE performance of CBP: 45 wt%BUBD-1 blend films and optoelectronic properties of corresponding OLED devices can be attributed to both the localized surface plasmon resonance (LSPR) effect and the increased hole mobility caused by the addition of Ag NPs. The introduction of Ag NPs to the hole transfer layer of OLED devices may provide a potential method to realize the electrically pumped OSLs with the planar structures.

Mechanical properties and failure mechanism analysis of basalt-glass fibers hybrid FRP composite bars

In order to solve the defect of insufficient performance of the single fiber reinforced plastic (FRP) bars. The basalt fibers and glass fibers are prepared into the basalt-glass fibers hybrid FRP composite bars (B/G hybrid FRP bars) in this paper. The failure mechanism of basalt-glass fibers hybrid FRP composite bars is analyzed by the finite element method. The main failure factors include not only fiber breakage but also the separation of the interface between the two fibers. The mechanical properties of basalt-glass fibers hybrid FRP composite bars in the alkaline environment are predicted by simulation. The tensile properties, elongation properties, pseudo ductility stage length, and yield stress reduction of basalt-glass fibers hybrid FRP composite bars under different fiber volume ratios are investigated by tensile tests. The results show that when the volume ratio of glass fiber to basalt fiber is 7:3, the ultimate strain reaches 2.57%. When the volume ratio of glass fiber to basalt fiber is 9:1, the ultimate strain reaches 3.06%, with a difference of 0.49%. In addition, the yield stress reduction stage in basalt-glass fibers hybrid FRP composite bars is also affected by the volume ratio of hybrid fibers. When the volume ratio of glass fibers to basalt fibers is 9:1 and 7:3, the difference in ultimate tensile strength and the difference in yield stress reduction stage of the two are 185.85 MPa and 145.09 MPa, respectively. In addition, the optimal volume ratio range suitable for different situations is summarized in the study. When glass fiber accounts for 68.9–100% of the total integral number of basalt-glass fibers hybrid FRP composite bars, the tensile and extension properties of basalt-glass fibers hybrid FRP composite bars have different degrees of change.

Serial lung mass volume ratios as prognostic indicators of neonatal respiratory morbidity in fetal pulmonary malformations

Several studies have shown that the congenital pulmonary airway malformation volume ratio is a useful prognosticator of neonatal outcome in prenatally diagnosed lung lesions. However, there remains a lack of consensus on which congenital pulmonary airway malformation volume ratio values have the best predictive value because of operator dependence, inherent changes in lung lesion size throughout gestation, and the widespread use of maternal steroids. This study sought to determine the association between serial congenital pulmonary airway malformation volume ratio measurements and neonatal outcomes among fetuses with lung malformations. This was a retrospective cohort study of fetuses with a prenatally diagnosed lung malformation managed at 2 major fetal centers from January 2010 to December 2021. Prenatal variables, including prospectively measured congenital pulmonary airway malformation volume ratio measurements (initial, maximum, and final), were analyzed. The results were correlated with 3 outcome measures, namely surgical resection before 30 days of life, a need for supplemental O2 at birth, and endotracheal intubation at birth. Statistical analyses were performed using receiver operating characteristic curve analyses, Welch 2 sample t tests, and multivariable logistic regressions (P<.05). There were 123 fetuses with isolated lung lesions identified. Eight (6.5%) had hydrops. The mean initial congenital pulmonary airway malformation volume ratio was 0.67±0.61 cm2 at 22.9±3.9 weeks' gestation. The mean maximum congenital pulmonary airway malformation volume ratio was 1.08 ± 0.94 cm2 at 27.0 ± 4.0 weeks' gestation. The mean final congenital pulmonary airway malformation volume ratio was 0.58±0.60 cm2 at 33.2±4.1 weeks' gestation. At a mean gestational age at delivery of 38.3±2.6 weeks, 15 (12.2%) underwent neonatal lung resection for symptomatic disease. In a multivariable regression, all 3 congenital pulmonary airway malformation volume ratio measurements showed a significant correlation with neonatal lung resection (P<.001). Optimal congenital pulmonary airway malformation volume ratio cutoffs were established based on an initial congenital pulmonary airway malformation volume ratio of ≥0.8 cm2, maximum congenital pulmonary airway malformation volume ratio of ≥1.5 cm2, and a final congenital pulmonary airway malformation volume ratio of ≥1.3 cm2 with associated areas under the curve of 0.89, 0.97, and 0.93, respectively. The final congenital pulmonary airway malformation volume ratio had the highest specificity for predicting surgical lung resection in the early postnatal period. Measuring congenital pulmonary airway malformation volume ratios throughout pregnancy in fetuses with pulmonary malformations has clinical value for prenatal counseling and planning care transition after delivery. Fetuses with a final congenital pulmonary airway malformation volume ratio of more than 1.3 cm2 are likely to require neonatal surgery and therefore should be delivered at tertiary care centers with a neonatal intensive care unit and pediatric surgical expertise.

Hollow core-shell nanocoatings with gradient refractive index structure for enhanced photovoltaic performance

Hollow structure-based multifunctional coatings with broadband antireflectivity, self-cleaning performance, stability, and durability can be applied to photovoltaic (PV) modules to maintain high transmittance and increase solar cell power generation. This research prepared bilayer hollow composite nanoparticles by improving and optimizing the nanoparticle synthesis and volume ratios. The optimal volume ratio of hollow SiO2 to TiO2 was determined using refractive index, transmittance, surface area, photocatalysis, and thermogravimetry. With the modification effect of methyltriethoxysilane, the refractive index interval of the composite coating was obtained, while giving the coating better hydrophobicity. A three-layer broadband antireflective coating (HT-TGBA) with a gradient refractive index structure was prepared using pre-designed simulation software. Various morphological and structural characterizations of HT-TGBA nanoparticles were performed. The transmittance of HT-TGBA-coated glass was significantly improved compared with that of uncoated glass. Its self-cleaning properties were confirmed by photocatalysis and surface hydrophobicity. Damp heat, abrasion tests, and pencil hardness tests proved the excellent durability of HT-TGBA, and measurements of sustained water contact angles demonstrated its stability. The short-circuit current density and photoelectric conversion efficiency were significantly improved by dip-coating HT-TGBA onto mini-modules. These results demonstrate that HT-TGBA has broad application prospects, supporting future large-scale applications of composite coatings in PV modules.

Enhancement of Power Conversion Efficiency of Non-Fullerene Organic Solar Cells Using Green Synthesized Au-Ag Nanoparticles.

Organic-based photovoltaics are excellent candidates for renewable energy alternatives to fossil fuels due to their low weight, low manufacturing cost, and, in recent years, high efficiency, which is now above 18%. However, one cannot ignore the environmental price of the fabrication procedure due to the usage of toxic solvents and high-energy input equipment. In this work, we report on the enhancement of the power conversion efficiency non-fullerene organic solar cells by incorporating green synthesised Au-Ag nanoparticles, using onion bulb extract, into the hole transport layer poly (3,4-ethylene dioxythiophene)-poly (styrene sulfonate) (PEDOT: PSS) of Poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3 fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)]: 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']dithiophene (PTB7-Th: ITIC) bulk-heterojunction organic solar cells. Red onion has been reported to contain quercetin, which serves as a capping agent that covers bare metal nanoparticles, thus reducing exciton quenching. We found that the optimized volume ratio of NPs to PEDOT: PSS is 0.06:1. At this ratio, a 24.7% enhancement in power conversion efficiency of the cell is observed, corresponding to a 9.11% power conversion efficiency (PCE). This enhancement is due to an increase in the generated photocurrent and a decrease in the serial resistance and recombination, as extracted from the fitting of the experimental data to a non-ideal single diode solar cell model. It is expected that the same procedure can be applied to other non-fullerene acceptor-based organic solar cells, leading to an even higher efficiency with minimal effect on the environment.

Probiotic Lactobacillus paragasseri K7 Nanofiber Encapsulation Using Nozzle-Free Electrospinning.

Probiotics are live microorganisms that can have beneficial effects on humans. Encapsulation offers them a better chance of survival. Therefore, nozzle-free electrospinning was introduced for their embedding in nanofibrous material. Probiotic Lactobacillus paragasseri K7 in lyophilized and fresh form, with and without inulin as prebiotic, was added to a polymer solution of sodium alginate (NaAlg) and polyethylene oxide (PEO). Conductivity, viscosity, pH, and surface tension were determined to define the optimal concentration and volume ratio for smooth electrospinning. The success of the formed nanoscale materials was examined by scanning electron microscope (SEM), while the entrapment of probiotics in the nanofibrous mats was detected by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). Spontaneous diffusion of bacteria from electrospun samples in PBS buffer pH 7.4 was studied by plate counting on MRS agar. By exposing polymer solutions containing L. paragasseri K7 and inulin to a high electric field, the nanofilm was formed on a polypropylene substrate, used as collecting material. When polymer solutions without inulin were used, the bead-like nanofibers may have become visible. The SEM results suggest that inulin, in addition to K7 strain, additionally lowers the conductivity of spinning macromolecular solution and hinders the nanofiber formation. The results of ATR-FTIR confirmed the presence of L. paragasseri K7 embedded in nanocomposites by the appearance of characteristic peaks. The samples containing the probiotic regardless of its form with inulin had similar surface composition, except that the sodium content was higher in the samples with fresh probiotic, probably due to greater and thus less easy embedding of the bacteria in NaAlg. Within 2 h, the largest amount of probiotic strain K7 was spontaneously released from the electrospun sample containing the inulin and probiotic in freeze-dried form (44%), while the amount released from the nanofibrous sample, which also contained the inulin and probiotic in fresh form, was significantly lower (21%). These preliminary results demonstrate the potential of nozzle-free electrospinning technology for the development of probiotic delivery systems for short-term use, such as feminine hygiene materials (tampons, pads, napkins).

A Green Binary Solvent Method to Control Organic Semiconductor Crystallization

AbstractWhile solution‐processed small‐molecular organic semiconductors have been reported with significant research progress, their random crystal orientations and abundant defects at grain boundaries remain as a major obstacle to achieving high performance in organic electronic devices. In this paper, we demonstrate a binary solvent method that comprises a green solvent to manipulate the crystal alignment, morphology and charge transport of organic semiconductors. 6,13‐bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) was studied as an example to showcase the enlargement of grain width and millimeter‐scale alignment of organic crystals based on the toluene/n‐amyl acetate binary solvents. At an optimized volume ratio of 3 : 1, the toluene/n‐amyl acetate binary solvent gave rise to a 4‐fold reduction in misorientation angle and approximately 40 % increase in the grain width. UV‐visible spectroscopy confirmed strong H‐aggregations with more favorable intrachain interaction and charge transport in TIPS pentacene. X‐ray diffraction showed enhanced peak intensities in (00 l) type of reflections and improved film crystallinity. Finally, thin film transistors were demonstrated to test the charge transport in the TIPS pentacene organic crystals. This work demonstrates the binary green solvent method can effectively regulate the organic semiconductor crystallization and alignment even in the absence of external alignment techniques such as solution shearing, and thereby sheds light on advancing facile organic electronic applications.

Magnetic, mechanical, electrical properties and coupling effects of particle reinforced piezoelectric polymer matrix composites

The 0-3 polymer-based magnetoelectric (ME) composites have the advantages of easy preparation, low cost, good flexibility, environmental friendliness and biological affinity, etc., and have a wide range of applications prospect in the biomedical field, such as the biological microelectronics, nanomedicine technology treatment, bone tissue healing and so on. The ME performance of this composite is jointly contributed by the properties of its component and microstructure. In this work, considering the impact of interphase effect, and the relationship between the effective properties of 0-3 ME composites and its microstructure is established, and the expressions of the Young's modulus, permeability, dielectric coefficient, piezoelectric coefficient, piezomagnetic coefficient and ME coefficient are obtained respectively. The effects of interphase properties and particle sizes on the effective properties of ME composites are discussed. By comparison, our theoretical results are in good agreement with experimental data. Then the influence of some factors on its effective performance is discussed. The results show that the effective properties of 0-3 ME composites are strongly dependent on the volume fraction ratio and size of the particles, the applied magnetic field. There is an optimal volume ratio and magnetic field to maximize ∂ α E 33 /∂ H 3 .

Effects of Wheat Tempering with Slightly Acidic Electrolyzed Water on the Microbiota and Flour Characteristics.

Slightly acidic electrolyzed water (SAEW) was prepared and used as wheat tempering water. This study explored the impacts of tempering with SAEW on microbial load and diversity and quality properties of wheat flour. As SAEW volume ratio increased, the residual level of total plate counts (TPC) and mould/yeast counts (MYC) decreased dramatically (p &lt; 0.05). Based on genomics analysis, bacterial 16S rRNA gene and fungal ITS1 gene region were performed to characterize the changes in microbial communities' composition and diversity in response to SAEW treatment. SAEW optimal volume ratio (6.5:10, v/v) of SAEW with distilled water influenced wheat microbiome composition, with a higher microbial diversity and abundance discovered on the control grains. Bacteroidetes of predominant bacterial phylum and Ascomycota of the most abundant fungal phylum were reduced after SAEW optimal volume ratio tempering. The flour yield is higher and ash content is lower than the control samples. Falling number and "b*" in terms of colour markedly increased. DSC (Differential Scanning Calorimetry) test showed that To (onset temperature), Tp (peak temperature), and Tc (conclusion temperature) were significantly decreased in thermal characteristics of flour. Gluten content, protein content, ΔH and pasting properties tests showed no significant change. It can be concluded that SAEW should be applied on wheat tempering for producing clean wheat flour. ANOVA and Tukey's honestly significant difference (HSD) test were used for the analysis of variance and differences between the experimental and control groups, with p &lt; 0.05.

Role of Bicontinuous Structure in Elastomeric Electrolytes for High-Energy Solid-State Lithium-Metal Batteries.

Solid-state lithium (Li)-metal batteries (LMBs) are garnering attention as a next-generation battery technology that can surpass conventional Li-ion batteries in terms of energy density and operational safety under the condition that the issue of uncontrolled Li dendrite is resolved. In this study, various plastic crystal-embedded elastomer electrolytes (PCEEs) are investigated with different phase-separated structures, prepared by systematically adjusting the volume ratio of the phases, to elucidate the structure-property-electrochemical performance relationship of the PCEE in the LMBs. At an optimal volume ratio of elastomer phase to plastic-crystal phase (i.e., 1:1), bicontinuous-structured PCEE, consisting of efficient ion-conducting, plastic-crystal pathways with long-range connectivity within a crosslinked elastomer matrix, exhibits exceptionally high ionic conductivity (≈10-3 S cm-1 ) at 20 °C and excellent mechanical resilience (elongation at break ≈ 300%). A full cell featuring this optimized PCEE, a 35µm thick Li anode, and a high loading LiNi0.83 Mn0.06 Co0.11 O2 (NMC-83) cathode delivers a high energy density of 437Wh kganode+cathode+electrolyte -1 . The established structure-property-electrochemical performance relationship of the PCEE for solid-state LMBs is expected to inform the development of the elastomeric electrolytes for various electrochemical energy systems.

Solvent‐Induced Anti‐Aggregation Evolution on Small Molecule Electron‐Transporting Layer for Efficient, Scalable, and Robust Organic Solar Cells

AbstractThe severe aggregation property of the small molecule electron‐transporting layer (ETL) not only deteriorates the photovoltaic performance and operational reliability but also constrains its compatibility with large‐scale coating techniques. Herein, by applying N,N′‐Bis{3‐[3‐(Dimethylamino)propylamino]propyl}perylene‐3,4,9,10‐tetracarboxylic diimide (PDINN) (a well‐known ETL) as a demo, a solvent‐induced anti‐aggregation (SIAA) strategy is proposed to cope with these hurdles via the mixing of ethanol and trifluoroethanol solvents at an optimal volume ratio. In situ photoluminescence and dynamic light scattering synergistically reveals the suppressed aggregation behavior of the SIAA‐treated PDINN dispersion during the film‐forming process. Owing to this amendment, the film quality and electron‐transport capability of the PDINN layer are remarkably enhanced. In consequence, based on the PM6:L8‐BO system, a champion power conversion efficiency (PCE) of 19.0% together with an impressive fill factor of 80.6% is harvested. A 1 cm2 device with an excellent PCE of 16.6% is also fabricated using the doctor‐blading SIAA‐treated PDINN ink. More strikingly, this SIAA treatment impels better reliability under long‐term shelf‐lifetime and thermal stress periods. This work provides a promising and tractable approach to address the inherent self‐aggregation issue of electron‐transporting materials, which is beneficial for the development of efficient and stable organic optoelectronic devices.

Performance analysis and operation strategy of a dual-evaporation temperature heat pump system for electric vehicles in winter

With increasingly serious environmental and energy issues, efficient and environmentally friendly electric vehicles have received more attention. However, the high heating and dehumidification energy consumption of their air conditioning system reduces their driving range in winter, giving passengers and drivers range anxiety. In this study, a dual-evaporation temperature heat pump system is proposed to reduce the energy consumption of electric vehicle air conditioning systems in winter, and a simulation model of the proposed system is developed. First, the volume ratio of the dual-cylinder compressor is optimized. Subsequently, the performance of the proposed system in various operation modes under different ambient conditions is compared. The results indicate an optimized volume ratio of 2.85, which is taken as the system’s design condition. The dual-evaporation temperature heating dehumidification mode shows superior performance compared with the conventional mode under typical winter conditions in three different climatic zones. Moreover, energy consumption can be reduced by reasonably controlling the operation mode based on ambient conditions. An operation strategy for the dual-evaporation temperature heat pump system in winter is proposed through the regional division of the psychrometric chart, and the energy-saving operation mode of the system is analyzed for different climate zones in China.

Research on chemical oxygen demand based on laser Fluorescence-Raman spectroscopy

In this invited paper, a novel water chemical oxygen demand (COD) detection method based on laser spectroscopy is proposed, and the COD value is obtained according to the intensity ratio of laser Fluorescence-Raman signal produced by laser incident into water. Based on the laser Fluorescence-Raman ratio (LFRR) method, we design a portable water quality measurement system. In which, a 405 nm semiconductor laser is used as the light source. The laser is coupled into the delivering port of Y-type fiber and then transmitted into water. The generated Mie scattered light, water Raman light and corresponding fluorescence are received and transmitted into spectrometer through the detecting port of Y-type fiber, and the COD value can be obtained by analyzing the LFRR of water spectra. The mixed solution of sodium humate and glucose is used as the COD standard solution to calibrate the designed system. The experiment results show that the optimal volume ratio of the two solutions is 1:29. When the COD of standard solutions is in the 1–12 mg/L concentration range, a good linear relationship can be found between the COD value and LFRR value with a correlation coefficient of 0.974. In addition, the COD of natural water samples are measured with LFRR method, the results of which are consistent with COD values obtained by rapid digestion spectrophotometry. Meanwhile, experimental results prove that the COD detection method proposed in this paper has the advantages of high sensitivity, high precision, high detection speed and simplicity, which can be widely used in various water areas for real-time COD monitoring.

Optimization Based on Toughness and Splitting Tensile Strength of Steel-Fiber-Reinforced Concrete Incorporating Silica Fume Using Response Surface Method.

The greatest weakness of concrete as a construction material is its brittleness and low fracture energy absorption capacity until failure occurs. In order to improve concrete strength and durability, silica fume SF is introduced into the mixture, which at the same time leads to an increase in the brittleness of concrete. To improve the ductility and toughness of concrete, short steel fibers have been incorporated into concrete. Steel fibers and silica fume are jointly preferred for concrete design in order to obtain concrete with high strength and ductility. It is well-known that silica fume content and fiber properties, such as aspect ratio and volume ratio, directly affect the properties of SFRCs. The mixture design of steel-fiber-reinforced concrete (SFRC) with SF addition is a very important issue in terms of economy and performance. In this study, an experimental design was used to study the toughness and splitting tensile strength of SFRC with the response surface method (RSM). The models established by the RSM were used to optimize the design of SFRC in terms of the usage of optimal silica fume content, and optimal steel fiber volume and aspect ratio. Optimum silica fume content and fiber volume ratio values were determined using the D-optimal design method so that the steel fiber volume ratio was at the minimum and the bending toughness and splitting tensile strength were at the maximum. The amount of silica fume used as a cement replacement, aspect ratio, and volume fraction of steel fiber were chosen as independent variables in the experiment. Experimentally obtained mechanical properties of SFRC such as compression, bending, splitting, modulus of elasticity, toughness, and the toughness index were the dependent variables. A good correlation was observed between the dependent and independent variables included in the model. As a result of the optimization, optimum steel fiber volume was determined as 0.70% and silica fume content was determined as 15% for both aspect ratios.

Proportional Optimization Model of Multiscale Spherical BN for Enhancing Thermal Conductivity

The power electronics tend to become miniaturized and multifunctionalized, such as thermal rotators, circuit breakers, and microchips, which have necessitated creating instruments for investigating thermal mechanisms and enhancing thermal conductivity. In this paper, we construct the heat flow network of spherical boron nitride (BN) and used multiscale spherical BN to improve the thermal conductivity of the composite synergistically. The multiscale spherical filler ratio optimization model based on the Dinger–Funk particle stacking theory is established, which obtained the optimal volume ratio of 0.224:0.374:0.402 with D50 of 20, 70, and 160 μm. Meanwhile, the effects of multiscale filler ratio, morphology, filler content, and temperature are investigated. The thermal conductivity of composites can reach up to 1.84 W/(m·K) at 20 vol %. Significantly, the thermal conductivity of composites is 4.82 W/(m·K) at 30 vol %, which is achieved by optimizing the multiscale filler and particle size distribution.