Working Parameters Research Articles

STUDY OF THE TECHNOLOGICAL PROCESS OF MECHANICAL DEHYDRATION OF FOOD PRODUCTION WASTE THROUGH MATHEMATICAL MODELING

The separation of wet dispersed materials is becoming an urgent task for the industry of Ukraine and other countries, especially in the food and processing industries. Solving this task can effectively solve the problem of efficient management of wastes such as alcohol grounds, beer grounds, beet pulp, coffee and barley sludge. After separation of the liquid phase from the waste (dewatering), the solid phase can serve as a soil conditioner, a useful additive to agricultural feed, be used as a high-calorie fuel, and have other beneficial uses in both the processing and agricultural industries. After separation of the liquid phase from the waste (dehydration), the solid phase can serve as a useful additive to agricultural feed or be used as a high-calorie fuel. The most promising method of separating wet dispersed waste is mechanical dehydration. This method provides high productivity, low energy consumption, which is hundreds of times less than when using thermal methods to achieve the required moisture level of waste. A promising type of equipment for the mechanical separation of wet dispersed waste is presses with a hydraulic drive. They are characterized by compact size, high energy efficiency and reliability, as well as the possibility of precise regulation of waste processing parameters. The article presents a diagram of an improved and highly efficient installation with a hydraulic drive for the separation of wet dispersed materials. A mathematical model is presented that connects the parameters of the separation process, the design characteristics of the installation and the physical and mechanical properties of the material being processed. The found equations can be used to establish relationships between the working parameters of the processes, the design parameters of the equipment for the efficiency of the proposed bioenergy waste recycling technology.

Viral Bronchiolitis Findings in Children at the Pediatric Clinic of Clinical Center of the University of Sarajevo

Bronchiolitis is a relatively common respiratory condition, usually presenting in the first two years of life. It is followed by audible phenomena, due to inflammatory airway obstruction. Common symptoms are nasal discharge, cough, tachypnoea, fever, and cyanosis. The cause is viral, most commonly respiratory syncytial virus. Bronchitis leads to respiratory acidosis and leads to accumulation of carbon dioxide. We analyzed 83 patients with a diagnosis of bronchiolitis at the discharge from the Pediatric clinic of the Clinical Center of the University of Sarajevo. We observed the relationships between acid-base status parameters, blood work parameters, age, and weight and placed them into groups based on whether they had any co¬morbidities or not. Patients without comorbidities showed significant differences in age, body temperature, and leukocyte count compared to patients with comorbidities. We also noted significant correlations be¬tween age, weight, hemoglobin level, hematocrit, erythrocyte count, pCO2, pH, and HCO3 which led to a conclusion that it is likely that in young children with bronchiolitis, the issue is not in the elimination of CO2 through lungs. Rather, it is the transport of CO2 to the lungs due to reduced erythrocyte count and so we believe, that if proven feasible, bronchiolitis could be treated with pure erythrocyte trans.

Mathematical models to forecast temporal variations of power law shape parameters of a PV module working in real weather conditions: Prediction of maximum power and comparison with single-diode model

In this study, an innovative approach has been proposed to generate real time current–voltage characteristics and forecast peak power of photovoltaic (PV) modules working outdoors beneath real meteorological conditions. Power-Law Model (PLM) including four unknown parameters, two PV metrics (ISC, VOC), and two profile parameters (γ, m), has been used for fast, accurate and reliable modelling of PV modules. Explicit expressions giving γ and m parameters as functions of cardinal point coordinates (IMPP,VMPP, ISC and VOC) have been established. A daily monitoring of PV quantities, throughout one reference day, has been used to derive novel mathematical models of γ and m depending on module temperature and solar irradiance. To describe PV module behavior under changing meteorological conditions during an arbitrary day, mathematical models have been called to reproduce dynamical values of PLM shape parameters γ and m. Reliability of the approach has been assessed by comparing current–voltage characteristics and maximum power coming from PLM and Single-Diode Model (SDM) to experimental data of twenty-two PV modules measured at NREL. Comparison also reveals that I-V characteristics generated and predicted separately by PLM and SDM parameters are very close. In some cases, I-V characteristics generated by PLM parameters are more accurate. Furthermore, NRMSE values for generated and predicted I-V characteristics for all kinds of PV modules evaluated for different working conditions do not exceed 4% for both PLM and SDM, and determination coefficient values for long-term prediction of maximum power are close to one and annual average value is greater than 0,95.

Evolution and prognostic value of left ventricular deformation and myocardial work parameters in transthyretin amyloid cardiomyopathy.

Wild-type transthyretin amyloid cardiomyopathy (ATTR-CM) is an increasingly recognized condition. It remains challenging to estimate the extent of disease and the prognosis for most patients. Myocardial work is a sensitive echocardiographic approach that improves the characterization of myocardial damage. We investigate the parameters of myocardial deformation and work in ATTR-CM patients and their changes over time. We analysed clinical, electrocardiographic, biological, and echocardiographic characteristics in 113 patients [median age 82 (77-85), 90.4% male] diagnosed with wild-type ATTR-CM based on international consensus at a single centre. We compared the data at baseline and 18-month follow-up. Thirty-four patients died and 12 were hospitalized for heart failure at a median follow-up of 935 days (interquartile range 691-1159 days). Left ventricular end-diastolic diameter, left atrial strain during reservoir phase (LASRES), left ventricular longitudinal strain, global work index (GWI), global constructive work significantly decreased from baseline to 18 months, while left ventricular wall thickness increased. Left ventricular ejection fraction, right ventricular free wall strain (FWS), global wasted work (GWW), and global work efficiency did not alter significantly. Strain parameters were identified as prognostic on baseline evaluation using a multivariate analysis: GWI, GWW, FWS, and LASRES. They were significantly associated with the risk of death and hospitalization for heart failure. Multi-chamber strain assessment may improve the surveillance of patients with ATTR-CM, and myocardial work parameters may improve clinical risk stratification in this population.

A Piezo‐Tribovoltaic Nanogenerator with Ultrahigh Output Power Density and Dynamic Sensory Functions

AbstractTribovoltaic nanogenerator (TVNG) mainly collects energy from sliding motions of two semiconducting materials, but it cannot effectively react to the pressure change in the vertical direction. Here, a piezo‐tribovoltaic nanogenerator (P‐TVNG) is proposed by integrating piezoelectric and tribovoltaic effects to collect energy from both the sliding motion and the variation of applied pressure. Hence, this P‐TVNG can gain extra performance improvement on the top of the original output limit of TVNG. The maximum output power density of P‐TVNG is up to 3.61 W m−2, which is 28.9 % higher than the highest record of the TVNG using similar materials. Additionally, the piezo‐module can work as a separated sensory component by switching the circuit, which can monitor and analyze various working parameters of TVNG. A series of dynamic characteristics of TVNG during its operation have been identified, including the hysteresis between output current and applied pressure, the influence and incompatibility of interface stress to output performance, and so on. As a multifunction of devices, this P‐TVNG system is possible to be applied in semiconductor industry, smart manufacturing, and many other fields. This work improves the performance of the TVNGs while extending its functionality, which broadens the application field of TVNG devices.

Design and optimization of intelligent orchard frost prevention machine under low-carbon emission reduction

In this paper, a self-heating small frost prevention machine is designed according to the agricultural frost prevention demand in mountainous and hilly areas. Firstly, the frost prevention machine's overall structure and key components are meticulously designed and modeled using UG 3D modeling software, tailored to the specific characteristics of the stepped planting environment in the mountainous area. At the same time, the flow field of the frost prevention machine is calculated and analyzed using jet diffusion theory and thermodynamic theory. The frost prevention machine's wind speed and temperature attenuation models are established, and subsequently fine-tuned and validated using Fluent to optimize its attenuation performance and operational range. To enhance frost prevention performance, a multi-objective bionic optimization strategy is applied to systematically optimize the structural and working parameters of the machine. Moreover, an adaptive mutation hybrid frog jump algorithm is introduced to further enhance the optimization accuracy. The simulation experimental results show that structural improvements can reduce axial speed and temperature attenuation loss by approximately 45%, while slightly increasing the machine's power consumption. On the other hand, optimizing working parameters enhances wind resistance and reduces overall power consumption. The actual experimental results show that the optimized frost prevention machine achieves a frost prevention coverage radius of 10 m within the orchard, even under maximum ambient wind speeds of 2 m/s, and it dynamically adapts to environmental changes. Additionally, the synergy of multiple frost prevention machines, powered by solar panels, enhances the overall frost prevention efficiency, leading to improved economy and reduced energy consumption.

Simulation and Optimization Experiment: Working Process of a Cleaning Device for Flax Combine Harvester

The aim of this study was to investigate the effects of different working parameters on the cleaning efficiency of a cleaning device during the separation and cleaning process in a flax joint harvesting machine. To achieve this objective, CFD–DEM joint simulation technology was used to construct a CFD model of the cleaning device and a DEM model of the discharged flax material; the simulation results show the flax cleaning process. The Box–Behnken experimental design method was used to establish a mathematical model between the vibrating sieve frequency, vibrating sieve amplitude, fan wind speed, seed impurity rate, and cleaning loss rate to find the optimum combination of cleaning equipment parameters and to conduct a field verification test. The simulation test results show that, when the vibrating sieve frequency is 6 Hz, the vibrating sieve amplitude is 14.42 mm, the fan wind speed is 5.96 m/s, and the machine cleaning effect is the best; the simulation test was measured following a seed impurity rate of 2.97% and cleaning loss rate of 2.17%. The field test verification results show that, after optimizing the working parameters of the cleaning device, the cleaning loss rate is 3.58% and the impurity rate of the grain combine harvester is 3.16%, thus meeting the national and industry requirements. The test results and simulation results are highly consistent with the model, thereby verifying the reliability of the model. The results of the study provide a reference for the design and performance optimization of the flax combine cleaner.

Advanced echocardiographic assessment in wild-type and hereditary transthyretin cardiac amyloidosis: the role of myocardial work and left atrial strain

Abstract Introduction Transthyretin cardiac amyloidosis (ATTR-CA) is a progressive infiltrative cardiomyopathy caused by extracellular deposition of insoluble transthyretin (TTR) amyloid fibrils in the myocardium. ATTR-CA can be classified as wild type ATTR-CA (ATTRwt-CA), caused by age-related misfolding of TTR, and hereditary ATTR-CA (ATTRv-CA), an autosomal dominant disease in which gene mutations lead to changes in TTR protein. Speckle tracking echocardiography and myocardial work (MW) analysis can better characterize left ventricular and left atrial (LA) function in ATTRwt-CA and in ATTRv-CA. Aims to investigate differences in myocardial work and left atrial strain parameters between patients affected by ATTRwt-CA and patients affected by ATTRv-CA. Material and methods 40 male patients affected by ATTR-CA were prospectively enrolled, distinguishing between 20 patients with ATTRwt-CA (76 ± 7 yrs) and 20 patients with ATTRv-CA (74 ± 6 yrs) (1 pts with Val30Met mutation, 6 pts with Val122Ile mutation; 8 pts with Glu89Gln mutation; 5 pts with Phe64Leu mutation). All underwent a transthoracic echcoardiogram to calculate global longitudinal strain (GLS), MW parameters and LA strain. Results No difference was found between the two groups (ATTRwt-CA vs ATTRv-CA) for what regards age (76 ± 7 vs 74 ± 6 yrs, p = 0,06), BMI (27,2 ± 2,2 vs 26,6 kg/mq; p = 0,3), BSA (1,8 ± 0,2 vs 1,7 ± 0,1 mq; p = 0,1) and left ventricle mass index (LVMi) (183,41 ± 45,2 vs 148,5 ± 47,3 g/mq; p = 0,07). In ATTRwt-CA patients, ejection fraction (EF) is lower, but without any statistical significance (50 ± 6,9 vs 54 ± 6,4 %, p = 0,06). On the other hand, in ATTRwt-CA patients GLS is significantly higher than in ATTRv-CA patients (-9,8 ± 3,2 vs -15,0 ± 2,5 %; p < 0,0001). Global work index (GWI) (853,6 ± 367,6 vs 1431,6 ± 318,3 mmHg%; p < 0,0001), global constructive work (GCW) (1169 ± 303 vs 1726,5 ± 310,3 mmHg %; p < 0,0001) and global work efficiency (GWE) (83,2 ± 9,4 vs 89 ± 5,3 %; p = 0,04) are significantly reduced in ATTRwt-CA in comparison with ATTRv-CA. For what regards atrial function, in ATTwt-CA patients LA reservoir (9,7 ± 3,7 vs 17,6 ± 7,5 %; p = 0,004) and LA ejection fraction (LAFE) (28,9 ± 13,6 vs 46,2 ± 8,9; p = 0,02) are reduced, while LA booster is higher (-2,5 ± 3,1 vs -10 ± 4,7 %; p < 0, 0001). Conclusion In patients with ATTR-CA advanced echocardiographic assessment can better differentiate left atrial and left ventricular involvement in ATTRwt-CA versus ATTRv-CA.TablesGraphs

Right ventricular global work efficiency provides the highest prediction for improvements in right ventricle to left ventricle diameter ratio with acute pulmonary embolism treatments

Abstract Introduction In addition to standard echocardiographic measures, global longitudinal strain (GLS) with speckle tracking (ST) and myocardial work (MW) evaluation have been used in the assessment of right ventricle (RV) function in patients with acute pulmonary embolism (PE). In this study we aimed to compare echocardiographic measures, ST and MW in prediction of change in right ventricle (RV) to left ventricle (LV) diameter ratio (r) with treatments. Methods Our study comprised 83 consecutive patients (female %54.6, age 59±14.9 years) who admitted to our hospital with diagnosis of acute PE and underwent evidence-based treatments. Echocardiographic evaluation including ST and MW were performed within first 24 hours of admission. NT-pro-brain natriuretic peptide (NT-proBNP), troponin, pulmonary embolism severity index (PESI) and Qanadli score, RV and LV global work index (GWI), global work efficiency (GWE), global constructive work (GCW) and global wasted work (GWW), and RV-GLS were evaluated. Primary end-point (PEP) of this study was the change in RV to LVr on computed tomography (CT), and generalized additive model (GAM) in addition to classical linear regression (LR) were utilized for prediction of change in RV/LVr with these measures. Results PESI score and RV/LVr at admission were 84.8±23.8 and 1.13±0.39, respectively. Unfractioned or low-molecular weight heparin were treatments of choice in patients. The change in RV/LVr after selected treatments were 0.356. Mean hospital stay and overall follow-up duration were 8.7±3.7 and 328.7±126.8 days, respectively. In-hospital and long-term mortality rates were 1.2% and 13.3% respectively. Correlation co-efficients for intra- and interobserver agreement of MW measures varied from 0.85 to 0.96. The LR revealed that pulmonary arterial systolic, diastolic and mean pressure estimates, fractional area change and RV annular tissue velocity were significantly related with changes in RV/LVr (p values; 0.02, 0.01, 0.004, 0.03 and 0.03, respectively). Moreover, RV-GWE compared with RV-GLS showed a higher prediction for improvements in the RV/LVr (p value were <0.001 and 0.049, respectively). Utilization of GAM increased R2 value (from 0.15 to 0.20), and decreased the complexity of model. RV-GWE showed a moderate correlation with RV-GLS (r=-0.56), RV-GWI (r = 0.42), RV-GCW (r=0.32), LV-GWW(r=-0.55), LV-GLS (r=-0.33), FAC (r=0.26), NT-proBNP (r=-0.38), troponin (r=-0.28) but not with other measures. Conclusions The RV GWE as a novel myocardial work parameter seems to provide a better prediction for improvements in the RV/LVr with acute PE treatments as compared to clinical, laboratory and other echocardiographic measures including GLS.Figure-1Figure-2

Global Constructive Work is associated with ventricular arrythmias after cardiac resynchronization therapy

Abstract Aim Non-invasive left ventricular (LV) pressure-strain loops provide a novel method for quantifying myocardial work by incorporating LV pressure in measurements of myocardial deformation. Early studies suggest that myocardial work parameters such as Global Constructive Work (GCW) could be useful and reliable in arrhythmia prediction particularly in patients undergoing cardiac resynchronization therapy. The aim of this study was to evaluate whether the magnitude of GCW was associated with occurrence of ventricular arrhythmias in patients after cardiac resynchronization therapy. Method and results Patients on guideline-recommended treatment with a cardiac resynchronization therapy defibrillator (CRT-D) were evaluated by 2D speckle-tracking echocardiography including measurements of GCW at least six months after implantation. The primary outcome was a composite of appropriate defibrillator therapy and sustained ventricular arrhythmia under the monitor zone. A total of 162 patients (mean age 66 years (±10), 122 males (75%)), were included. 16 (10%) patients experienced the primary outcome during a median follow-up of 18 months (IQR: 12-25) after the index echocardiography. Patients with below-median GCW (<1,473 mmHg%) had a hazard ratio for the outcome of 8.14 [95% CI: 1.83-36.08], P=0.006 compared to patients above the median in a univariate model and remained an independent predictor after multivariate adjustment for eGFR and QRS duration (hazard ratio 4.75 [95% CI: 1.01 – 22.28], P<0.05. Conclusion In patients treated with CRT-D, GCW below median level was associated with a 5-fold increase in risk of ventricular arrhythmias.

Study on the Influence of Grooved-Wheel Working Parameters on Fertilizer Emission Performance and Parameter Optimization

The grooved-wheel fertilizer machine is one of the most widely used pieces of fertilization equipment. However, detailed information on the fertilizer filling status and the mechanism of particle interactions during the operation of the grooved wheel remains limited. To delve into the underlying mechanisms through which working parameters affect fertilization performance, this study, building upon prior research, conducted a qualitative analysis and numerical investigation of fertilizer particles using the Discrete Element Method. The analysis examined the impact of three working parameters, namely the grooved-wheel speed, working length, and forward speed of the fertilization equipment, on the morphology, forces, and kinetic properties of the fertilizer particles. Combining this analysis with orthogonal experimental research, we optimized the aforementioned working parameters. Both simulation and benchtop experimental results indicate that the grooved-wheel speed and working length influence the fertilizer filling status, while the forward speed of the equipment has no effect on the filling status. The connection between fertilizer force and kinetic changes is influenced by particle-free space. The lowest coefficient of variation (CV) for fertilization uniformity was observed at the grooved-wheel speed of 53.64 r/min, the wheel working length of 33.45 mm, and the forward speed of 0.7–1 m/s. The research findings contribute to a better understanding of the influencing mechanism of particle movement and fertilization outcomes in the operation of grooved-wheel fertilizer spreaders. This understanding enables precise control of the fertilizer application process, facilitating accurate and efficient fertilization. As a result, it enhances fertilizer utilization rates and reduces agricultural costs.

Finite element analysis and experiment of cutting rape shoot stalks based on Ansys

The cutting device is a key component of the rape shoot stalks harvester, and currently there is little research on the cutting device for edible rape shoots. Based on the material characteristics of edible rape shoot stalks, this paper conducts mechanical and finite element analysis on the cutting device to ensure low-resistance and high-efficiency cutting operations. Slip cutting angle of the cutter is set at 20° to ensure that the stalk is clamped during cutting, and the cutting speed ratio of the cutter is determined to be 0.8 to avoid missed cuts and overcuts. The cutting angle of inclination is upward to assist the post-cutting rape shoot stalks to tilt backward. The maximum cutting stress and cutting energy consumption of the blade are used as evaluation indicators for the experiment. Through single-factor simulation experiments, it is found that the cutting speed and cutting angle of inclination have a significant impact on the low-resistance and high-efficiency cutting of the device. Through multi-factor simulation experiments, the optimal working parameter combination of the device is determined to be a cutting speed of 0.3 m/s and a cutting angle of inclination of 7.13°. At this working parameter, the device can achieve low-resistance and high-efficiency cutting, and it has been verified that the cutting device can cut the stalk in one go with a smooth cut without tearing. This paper provides a theoretical basis for the design and parameter determination of the cutting device for vegetable rape shoot stalks harvesters.

Effects of different working parameters on the turbulent drag reduction regulated by annular plasma synthetic jet actuators

Reduction of turbulent drag force is one of important works in the design of airplanes and hypersonic aircrafts. The annular plasma synthetic jet (APSJ) has become an interesting and popular flow control method in reducing the drag of turbulent boundary layers. In this paper, a comprehensive experimental study is carried out on the turbulent drag reduction regulated by an array of annular plasma synthetic jet actuators. The effects of the operating parameters such as the actuation voltage, the pulse frequency and the incoming wind speed on the drag reduction rate are studied and discussed in detail. The performances of the plasma actuator array are evaluated and summarized at multiple working conditions. Finally, the coherent structures of turbulence and the hairpin-like vortices are depicted and discussed. The results show that the optimal drag reduction rate is achieved, as the actuation voltage, pulse frequency and incoming wind speed are Vpp = 7 kV, fp= 50 Hz, and U∞ = 7 m/s, respectively. A resonant coupling phenomenon is observed when the pulse frequency of the actuators approaches the characteristic frequency of the coherent structure. The upward sweep flow induced by APSJ actuators may lead to a reduction of the turbulent drag force, but the downward wash flow leads to an increase in the drag. Present study could provide solid experimental data and a helpful guidance for the drag reduction of an airplane.

Numerical analyses ridge-forming for whole film-mulching and double ridge-furrow, a discrete element method

The Northwest of China is a typical production mode of rain-fed agriculture, which mostly adopts the whole film-mulching and double ridge–furrow technique to address the difficulty of surface water storage. However, the quality of ridge formation directly affects the water storage on both sides of the ridges, the reliability of plastic film mulching, and the crop growth. This study focused on the process of rotary tillage ridging, took different inclination angles and depths of ridger as variable factors, explored the influence of different operation parameters on the quality of ridge forming. The soil viscoelastic model was established in the study using the discrete element method. The changes in ridger resistance, ridge structure, and soil particle disturbance were analyzed in detailed, respectively. The results indicated that as the inclination angles and depths of ridger increased, the resistance of ridger also increased. The height of the ridges significantly influenced by the inclination angles and depths of ridger, and under the same inclination angles of ridger, the height of the ridges was directly proportional to the depth of ridger. Under different combinations of operational parameters, the height of the small ridges had good agreement with the ridging agronomy. As for the large ridges, when the depth of ridger was 100 mm and the inclination angles were 15°, 30°, and 45°, the working parameters met the agronomic requirements for ridge forming. In terms of soil disturbance, the soil located within a range of 30–90 mm from the surface was most susceptible to disturbance from the rotary tillage and the ridger, and the soil disturbance was stronger in the small ridges compared to the large ridges. The results of study contributed to a deeper understanding of the rotary tillage ridging process and provided insights into the factors influencing the quality of ridge forming.

Research on intelligent compaction stiffness index and its application based on three-degree-of-freedom elastic–plastic dynamical model

CMV (Compaction Meter Value) and stiffness coefficient ks are the two most commonly used indexes in the intelligent compaction technology for subgrade soil. However, the applicability of CMV is affected by the operation mode and the working parameters of the vibrating roller. The calculation model of stiffness coefficient ks does not consider the plastic characteristics of the soil and the data usage rate of its calculation method is low. As a result, the current ICMVs (intelligent compaction measurement values) are only applicable to the compaction quality characterization in the later stage of compaction, and the accuracy and applicability of the compaction quality characterization in the whole process of construction are low, which limits the application of intelligent compaction technology. In view of the above problems, this paper aims to establish a comprehensive stiffness coefficient index which is not affected by the operation mode of the roller, comprehensively reflects the elastic–plastic mechanical properties and has strong resistance to accidental factors, in order to provide an accurate basis for the characterization of subgrade soil compaction quality. Firstly, a numerical simulation model of subgrade soil vibrating compaction with real-time change of soil Mohr-Coulomb model parameters with triaxial strain response is established, which provides accurate data support for ICMV calculation. Secondly, the calculation model and application method of CMV and ks are analyzed. Aiming at the shortcomings of the two indexes, the comprehensive stiffness coefficient kcs reflecting the elastic–plastic characteristics of soil and its complete calculation method are established. Finally, based on the simulation data, the accuracy of kcs is verified, and the variation law of the kcs calculation model parameters and the evolution mechanism of soil elastic–plastic properties are clarified. Based on the field tests data, the accuracy of kcs is verified. The results show that the deciding coefficients between kcs and compaction degree obtained by numerical simulation and field test are R2 = 0.83 and R2 = 0.72, respectively, which are higher than that between ks and compaction degree (R2 = 0.72, R2 = 0.52) and that between CMV and compaction degree (R2 = 0.04, R2 = 0.23). The accuracy of kcs to characterize compaction quality is higher, and it can maintain high stability during field application. During the compaction process, the elastic–plastic mechanical properties of subgrade soil evolve continuously, and each parameter of kcs calculation model increases with the rolling pass.

EECO: An AI-Based Algorithm for Energy-Efficient Comfort Optimisation

Environmental comfort takes a central role in the well-being and health of people. In modern industrial, commercial, and residential buildings, passive energy sources (such as solar irradiance and heat exchangers) and heating, ventilation, and air conditioning (HVAC) systems are usually employed to achieve the required comfort. While passive strategies can effectively enhance the livability of indoor spaces with limited or no energy cost, active strategies based on HVAC machines are often preferred to have direct control over the environment. Commonly, the working parameters of such machines are manually tuned to a fixed set point during working hours or throughout the whole day, leading to inefficiencies in terms of comfort and energy consumption. Albeit effective, previous works that tackle the comfort–energy tradeoff are tailored to the specific environment under study (in terms of geometry, characteristics of the building, etc.) and thus cannot be applied on a large industrial scale. We address the problem from a different angle and propose an adaptive and practical solution for comfort optimisation. It does not require the intervention of expert personnel or any customisations around the environment while it implicitly analyses the influence of different agents (e.g., passive phenomena) on the monitored parameters. A convolutional neural network (CNN) predicts the long-term impact on thermal comfort and energy consumption of a range of possible actuation strategies for the HVAC system. The decision on the best HVAC settings is taken by choosing the combination of ON/OFF and set point (SP), which optimises thermal comfort and, at the same time, minimises energy consumption. We validate our solution in a real-world scenario and through software simulations, providing a performance comparison against the fixed set point strategy and a greedy approach. The evaluation results show that our solution achieves the desired thermal comfort while reducing the energy footprint by up to approximately 16% in a real environment.

Investigation of water absorption performance of polyester‐woven fabrics coated with super absorbent polymer

AbstractSuperabsorbent polymers (SAPs) constitute a special class of polymers widely used in various fields, especially in the hygiene and healthcare sectors. This study investigates the feasibility of achieving high water absorption capacity surfaces by coating powdered SAP using conventional coating methods onto textile surfaces. For this purpose, water‐based coating pastes containing micronized SAP powder based on acrylamide/acrylic acid copolymer were coated onto polyester (PES)‐woven fabric surfaces using a knife‐over‐roll coating technique. As the working parameters, the pH value of the coating paste, the coating thickness (the distance between the cloth and the knife), the drying/fixing temperature and time, the SAP concentration, and the water absorption capacity according to time were investigated. The results were evaluated by applying the coating thickness, the amount of coating material transferred to the fabric on the SAP‐coated samples, water absorbing capacity, and centrifugal water retention tests. The obtained results have demonstrated that textile surfaces with high water absorption capacity (on average 200%–350%) can be achieved by coating hydrophobic fabric surfaces, such as PES, with SAP under suitable conditions.

Study on characteristics and parameter optimization of medical waste crushing process

Non-incineration friction heat treatment (FHT) technology has become an advanced medical waste treatment nowadays. To investigate the influence of different working parameters on crushing characteristics during FHT, the process of medical waste crushing with mixed materials (PE, PVC, SiO2) was studied and simulated based on discrete element method (DEM) by adopting the Hertz-Mindlin contact model and Tavares crushing model. The effects of different transverse blade contact angles (68° ∼ 102°), knife shaft speed (920–1000 r/min) and material ratio (1–5) for the crushing process were obtained. Using the maximum wear depth of transverse blade and the average particle size after crushing as the target response, an improved genetic algorithm was used to optimize the process parameters. With a comprehensive evaluation method, the best combination of parameters for the crushing process was determined: transverse blade contact angle of S68°, knife shaft speed of 1000 r/min, material ratio (plastic: glass) of 5:1.

Temperature Reliability Investigation for a 400 W Solid-State Power Amplifier under High and Cold Conditions

In order to study the temperature reliability of high-power amplifiers under high cand cold conditions, a 400 W solid-state power amplifier was taken as an example to explore the variation in its performance. The test results showed that its output power, gain, and power-added efficiency increased with the increase in temperature at a fixed frequency. Under a fixed input power, Pout and gain both showed different trends with the rising temperature. Within the frequency band of 2–10 MHz, the higher the temperature, the better the output power and gain. However, within the frequency range of 10–30 MHz, the higher the temperature, the worse the performance. Moreover, with the increasing temperature, its power-added efficiency, the second harmonic and the third harmonic also showed a decreasing trend. Detailed analysis showed that the degradation and inversion of performance parameters are closely related to the zero temperature coefficient and self-heating effect of the lateral double-diffused metal–oxide–semiconductor field-effect transistor. Meanwhile, it is also affected by the circuit structure and thermal design of the PA. In order to ensure stable performance in different environments, performance degradation can be improved by hardware compensation. Therefore, analyzing the working parameters at different temperatures for high-power PAs is the key to achieving temperature control and ensuring their long-term stability and reliability. This can provide relatively accurate reference data for subsequent heat dissipation optimization, greatly improve design efficiency, and even shorten the development cycle and reduce costs.

Photoelectrocatalytic degradation of pharmaceuticals promoted by a metal-free g‑C3N4 catalyst

Graphitic carbon nitride (g-C3N4) recently emerged as a remarkable photoelectrocatalyst for water treatment. Advanced oxidation processes (AOPs) consisting of photoelectrocatalytic (PEC) systems are being researched towards the development of sustainable strategies for the complete removal of refractory contaminants from effluents of urban wastewater treatment plants (WWTPs). This work consists of the optimisation of a PEC system, composed of a boron-doped diamond (BDD) anode, titanium cathode, and a suspended g-C3N4 photoelectrocatalyst, for the treatment of both synthetic and real urban waste waters spiked with pharmaceutical active compounds (PhACs). Different working parameters were considered and optimised to improve degradation and mineralisation rates, such as the cathode material, anode-to-cathode distance, electrolyte resistivity, and matrix composition. The optimal conditions allowed removals of 100 % diclofenac, 88 % fluoxetine and 77 % ibuprofen in the complex wastewater matrix. Moreover, it was observed that the presence of other refractory organic molecules offered a greater impediment to PEC treatment than residual co-existing substances. The main oxidative agents were investigated by scavenging experiments, showing that generated holes and reactive oxy-species, i.e. hydroxyl and superoxide radicals, take a major role in the degradation of PhACs. The recyclability of the g-C3N4 suspension as photoelectrocatalyst in the PEC process provides a promising perspective for the development of wastewater treatment units.