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To achieve uniform reaction temperature in flat-plate digital polymerase chain reaction (dPCR), we propose a multi-factor coupled thermal simulation method for the structure of flat-plate digital PCR using finite element analysis. This will help us obtain the optimal method for the structure of flat-plate dPCR. Thermal simulations were conducted to analyze the effects of forced air cooling, thermoelectric cooler (TEC) arrangement spacing, and heat-conducting plate thickness on the temperature uniformity of the flat-plate dPCR. The resulting isothermal surfaces and velocity magnitude vectors were used to summarize the impact of each factor. The study found that maintaining a mechanical fan speed of 3000 revolutions per minute (RPM) ±10 % during the heating period resulted in a 29.3 % reduction in the standard deviation of the temperature on the surface of the heat-conducting plate. Additionally, when the TEC spacing was between 2 mm and 3.5 mm, the standard deviation of the temperature on the plate's surface decreased by 87.1 % to 93.4 %. When the thickness of the thermal plate ranges from 3.5 mm to 4.5 mm, the standard deviation of the temperature on the surface of the thermal plate varies by approximately 0.006. The experimental results, obtained by sampling and analyzing the temperature on the surface of the thermal plate, are consistent with the simulation results. This proves that the method is informative in determining the structural parameters of the dPCR to enhance temperature uniformity. [ABSTRACT FROM AUTHOR]

Considering the green transformation, more and more attention must be paid to reducing noise pollution, which is one of the most important environmental problems today. Internal combustion engine (ICE) powered hand tools and small appliances, such as leaf blowers, brush cutters, chainsaws, and lawn mowers, are examples of the most undesirable sources of noise in today's human environment. This paper discusses the acoustic properties of a novel and compact silencer for a small twostroke ICE and proposes a novel concept with corresponding acoustic properties. The proposed solution has been measured on a test bench, and its properties, including transmission loss (TL) and reflection and absorption properties, have been experimentally determined. Using 3D printing technology and technological advantages, an innovative silencer with up to two microperforated (MP) panels, integrated into the expansion chamber of the original silencer, has been applied for rapid prototyping. As a result, noise reduction has been increased by at least 20 dB in the frequency range 800-4000 Hz. [ABSTRACT FROM AUTHOR]

Organic electrodes in aqueous batteries rely on electrochemical redox reactions for charge and discharge. The organic cathode at a discharged state can be spontaneously oxidized when exposed to air, which facilitates the development of air‐charging batteries. However, polymer cathodes in aqueous rechargeable Zn‐ion batteries (ARZIBs) generally show low discharge median voltage below 1 V. Herein, a new polymer cathode is reported that is prepared by electrodepositing poly(4‐hydroxydiphenylamine, HDPA) onto mesoporous activated carbon and shows a relatively high discharge voltage plateau at ≈1.1 V when coupled with a Zn anode. Its self‐charging performances at different conditions are investigated. Also, a high areal capacity of 3.8 mAh cm−2 of the cathode is achieved. The poly(4‐HDPA) contains both amino and carbonyl groups, and the carbonyl group is found to be fully responsible for redox reaction. Further investigation suggests that both Zn2+ and H+ in the ZnSO4 electrolyte participate in the charge storage process, and the H+ plays a dominant role. The air‐charging mechanism of this polymer cathode is elucidated both experimentally and theoretically. To demonstrate the practical applications, prototypes of box‐shaped battery pack are air‐charged to either drive a mini electric fan or light up LEDs. [ABSTRACT FROM AUTHOR]

A vicious cycle exists when higher global temperatures increase the demand for indoor air-conditioning, which consumes significant energy while heating the outdoors. These higher outdoor temperatures then prompt more air-conditioning use. This unsustainable cycle motivated us to develop an intervention to encourage more energy-efficient temperature adjustments during warm ambient conditions. We explored whether an experimental thermostat interface, which incorporated mechanical fans, affected individual thermostat-setting behavior. Experimental parameters were (1) feel versus don't-feel fans and (2) high-versus low-visibility fans. Participants were 23 university students, including 20 enrolled in an introductory psychology course. When prompted to make temperature adjustments, we found that participants who felt the fans selected higher (more energy-efficient) temperatures in warm ambient conditions. This effect held regardless of whether participants could clearly see the fans or not. These results inform how products can be designed to increase energy-conscious behaviors. [ABSTRACT FROM AUTHOR]

The control of mechanical energy loss is especially key in the design of permanent magnet drive motors for special vehicles. This paper takes a 300 kW high-efficiency motor as an example, and under the operating condition of 9000 rev/min, in order to control the size of the mechanical loss P m e c h , improve the efficiency of the motor, as well as enhance the ventilation and heat dissipation performance of the motor, the structural parameters of the motor's Axis fan are identified by using the Reverse Engineering (RE), and the fan performance is simulated and analysed by using the standard k-ε turbulence model of Computational Fluid Dynamics. The mechanical loss calculation model is investigated, and the effects of different blade numbers, wrap angles, and mounting angle parameters of the fan on the mechanical loss P m e c h are derived. And finally, the scheme is calculated to show that when the blade number Z is 13, the wrap angle Δ φ is 60°, the front mounting angle Φ 1 is 45°, and the rear mounting angle Φ 2 is 30°, the mechanical loss P m e c h decreases from 8.0 kW to 2.54 kW, and the motor efficiency η 0 is greatly improved, increasing from 94.2% to 96.1%. Meanwhile, based on finite element simulation experiments, the effects of the motor Axis fan on the steady-state temperature field of the pre-optimised and post-optimised fans are compared, and the optimised axis fan makes the motor ventilation and heat dissipation more reasonable. The maximum temperature of the motor under the same working condition decreased by 16.7 K, the efficiency η 0 of this motor was greatly improved, and the efficiency η 0 increased from 94.2% to 96.1%. [ABSTRACT FROM AUTHOR]

Due to the complexity of control mechanisms, vertical take-off and landing (VTOL) aerial vehicles have not found their way into widespread commercial use. Thanks to the availability of advanced technology, it is possible to develop simpler systems. Such systems could be used in transportation, the military, surveillance, etc. The research work is aimed at proposing an automatic stabilisation control algorithm solution for the VTOL hover flight phase. A critical analysis of the existing research work on a similar topic is provided. A flight platform and a suitable test bench for non-destructive tests were developed and presented in the current paper. The flight platform actuator system consists of two counter-rotating electric ducted fan (EDF) thrust motors and two servo systems that control pitch and roll movements. Moreover, the paper presents control algorithm development, structure, and experiments that confirm the proposed solutions. The results of the research work provide a solid foundation for developing the VTOL aerial vehicle, and the test bench prototype demonstrates a concept that can be further used on various flight platforms. [ABSTRACT FROM AUTHOR]

Due to the complexity of control mechanisms, vertical take-off and landing (VTOL) aerial vehicles have not found their way into widespread commercial use. Thanks to the availability of advanced technology, it is possible to develop simpler systems. Such systems could be used in transportation, the military, surveillance, etc. The research work is aimed at proposing an automatic stabilisation control algorithm solution for the VTOL hover flight phase. A critical analysis of the existing research work on a similar topic is provided. A flight platform and a suitable test bench for non-destructive tests were developed and presented in the current paper. The flight platform actuator system consists of two counter-rotating electric ducted fan (EDF) thrust motors and two servo systems that control pitch and roll movements. Moreover, the paper presents control algorithm development, structure, and experiments that confirm the proposed solutions. The results of the research work provide a solid foundation for developing the VTOL aerial vehicle, and the test bench prototype demonstrates a concept that can be further used on various flight platforms. [ABSTRACT FROM AUTHOR]

The technological installations' characteristics are possible to improve by equipping fans with a frequency-controlled electric drive. However, it can lead to an electromagnetic compatibility problem in the electrical supply system. This problem becomes worse if a large number of fans are included in the technological installation and the electric drives are powered from a substation connected to a limited power source. As an example, in this article we investigate the power supply system of a gas cooling unit with variable-frequency electric drives for fans. The electric drives' operating mode dependences characterizing the non-sinusoidal voltages and currents of the power source are obtained with the help of simulation modeling in the MATLAB environment with the Simulink expansion package. The typical substation circuit usage for the power supply of a group of fans with a frequency-controlled drive does not meet the requirements of IEEE Standard 519-2014. We can solve the problem of electromagnetic compatibility by changing the substation topology and organizing DC busbars and replacing frequency converters with inverters. We proposed forming DC busbars using 12-pulse rectifiers powered by transformers with two secondary windings with different connection schemes. The simulation results confirmed that the proposed substation topology provides the voltage and current harmonics level on the substation power busbars in accordance with the IEEE Standard 519-2014 requirements over the entire frequency range of the fans' motor control. [ABSTRACT FROM AUTHOR]

Digital twins technology (DTT) is an application framework with breakthrough rules. With the deep integration of the virtual information world and physical space, it becomes the basis for realizing intelligent machining production lines, which is of great significance to intelligent processing in industrial manufacturing. This review aims to study the application of DTT and the Metaverse in fluid machinery in the past 5 years by summarizing the application status of pumps and fans in fluid machinery from the perspective of DTT and the Metaverse through the collection, classification, and summary of relevant literature in the past 5 years. The research found that in addition to relatively mature applications in intelligent manufacturing, DTT and Metaverse technologies play a critical role in the development of new pump products and technologies and are widely used in numerical simulation and fault detection in fluid machinery for various pumps and other fields. Among fan-type fluid machinery, twin fans can comprehensively use technologies, such as perception, calculation, modeling, and deep learning, to provide efficient smart solutions for fan operation detection, power generation visualization, production monitoring, and operation monitoring. Still, there are some limitations. For example, real-time and accuracy cannot fully meet the requirements in the mechanical environment with high-precision requirements. However, there are also some solutions that have achieved good results. For instance, it is possible to achieve significant noise reduction and better aerodynamic performance of the axial fan by improving the sawtooth parameters of the fan and rearranging the sawtooth area. However, there are few application cases of the Metaverse in fluid machinery. The cases are limited to operating real equipment from a virtual environment and require the combination of virtual reality and DTT. The application effect still needs further verification. [ABSTRACT FROM AUTHOR]

The objective of this study was to quantify the influence of ventilation methods on children's exposure to indoor particles in a daycare center located in an urban area. The ventilation methods applied to the center were monitored for 1 year. It appears that indoor PM10 and PM2.5 concentrations of the center were basically determined by outdoor conditions. The fluctuations in outdoor particle concentration also affected the ventilation behavior during class. The windows and doors of the classroom were frequently closed during both class hours and nights when the outdoor particle concentrations were at high levels. Statistically significant differences in the I/O ratios were found among the ventilation methods. The PM10 I/O ratio with the closed windows was significantly higher (p < 0.01) than that with the open windows, and when the mechanical fans were operated, the I/O ratio dramatically decreased (p < 0.01). The I/O ratio of PM2.5 showed a similar trend to that of PM10 except for the mechanical fan operation. The filters rated lower than MERV 11 appear to be insufficient to remove submicron particles from the mechanically supplied outdoor air when the PM2.5 concentrations are high, such as during the heating period. [ABSTRACT FROM AUTHOR]

This paper presents a review of mobile positive pressure ventilation fans for use in rescue operations available on the European market in correlation with the approval regulations of the drive units. The authors determined the approval limits for harmful compound emissions by their power units, as applicable within the European Union. The purpose of this paper is to estimate the emissions of harmful compounds from the exhausts of rescue fan power units. It was demonstrated that electric fans are not in direct competition with internal combustion fans because they are provided in different power ranges, and 74% of the electric fan market falls between 1.1 kW and 2.2 kW, whereas fans powered by combustion engines are offered in a much higher power range from 0.7 kW to 92 kW, and the most popular power range offered by manufacturers is from 3.4 kW to 6.3 kW (57% of the market). On the basis of the limits derived from approval tests it can be demonstrated that 90% of engines on the European market which are used in fans (spark ignition (SI) engine up to 19 kW) are allowed carbon monoxide (CO) emissions of 610 g/kWh and hydrocarbon and nitrogen oxide emissions (HC + NOx) of 8 g/kWh. [ABSTRACT FROM AUTHOR]

Increasing air movement can alleviate or exacerbate occupational heat strain, but the impact is not well defined across a wide range of hot environments, with different clothing levels. Therefore, we combined a large empirical study with a physical model of human heat transfer to determine the climates where increased air movement (with electric fans) provides effective body cooling. The model allowed us to generate practical advice using a high-resolution matrix of temperature and humidity. The empirical study involved a total of 300 1-h work trials in a variety of environments (35, 40, 45, and 50 °C, with 20 up to 80% relative humidity) with and without simulated wind (3.5 vs 0.2 m∙s−1), and wearing either minimal clothing or a full body work coverall. Our data provides compelling evidence that the impact of fans is strongly determined by air temperature and humidity. When air temperature is ≥ 35 °C, fans are ineffective and potentially harmful when relative humidity is below 50%. Our simulated data also show the climates where high wind/fans are beneficial or harmful, considering heat acclimation, age, and wind speed. Using unified weather indices, the impact of air movement is well captured by the universal thermal climate index, but not by wet-bulb globe temperature and aspirated wet-bulb temperature. Overall, the data from this study can inform new guidance for major public and occupational health agencies, potentially maintaining health and productivity in a warming climate. [ABSTRACT FROM AUTHOR]

• A thermoelectric refrigeration system with ionic wind fans operates ultra-quietly. • Optimal operational parameters were obtained to maximize the performance. • Experimental COP was equivalent to the system with mechanical fans. • Experimental refrigeration capacity reached 8 W under 30 K difference. Conventional compression refrigeration systems generate considerable noise and vibration. The noise results in serious, negative impacts on people. Thermoelectric refrigeration technologies are considered a potential way to overcome these challenges. A novel thermoelectric refrigeration system, wherein thermoelectric chips are coupled with ionic wind fans, is proposed. Its performance was experimentally investigated and compared with theoretical results. The actual operating noise of the thermoelectric refrigeration system is only 4.2 dB(A), which is much lower than the maximum noise value that does not affect sleep. From experiments under different operating conditions, the optimal operating voltage of the thermoelectric chip is 5.5 V at 283.15 and 313.15 K on the cold and hot sides. The maximum coefficient of performance (COP) values reaches 0.28 and 0.31, which are equivalent to those of a system coupled with mechanical fans. Additionally, an ionic wind fan has an optimal operating voltage of 10.8 kV to maximize its air supply efficiency. Notably, such an operating voltage might be distinguished from the optimal voltage that achieves maximum operational performance for the new system. When the operating voltage of the thermoelectric chip is 5 V, the optimal operating voltage to obtain a maximum COP of 0.31 is 11.1 kV. Moreover, the experimental refrigeration capacity is greater than 8 W. The new system shows the ultra-quiet ability to operate at a large refrigeration capacity, and has good potential in applications, such as advanced refrigeration, building air-conditioning and ventilation systems. [ABSTRACT FROM AUTHOR]

In this paper, a robust control strategy is developed for unmanned helicopter prototype to simultaneously deal with random wind disturbances and remote communication delays. First, in the helicopter system modeling, the wind gust is not only treated as bounded external load disturbance, but propeller force-thrust coefficient variation that is caused by wind disturbance is also considered. Then, by equivalently treating the remote communication delays as random input delays, a robust attitude controller with energy-to-energy performance is developed for the helicopter system. Lyapunov-Krasovskii functions are utilized to analyze the stability of the proposed robust attitude controller. The gains of controller are calculated by solving linear matrix inequalities. Finally, by selecting Quanser's three degrees of freedom(3-DOF) helicopter prototype as the test bench, three groups of comparative tests are carried out respectively, in which electric fan is utilized to generate external wind gusts while random delays are added to the feedback loop. Compared with conventional H-infinity controller, the effectiveness as well as superiority of proposed control approach is well verified. [ABSTRACT FROM AUTHOR]

This study investigated the efficacy of voluntary fan utilization on autonomic thermoeffector responses and thermal perceptions during passive heating by lower leg immersion (42 °C) in a 27 °C ambient temperature, 50% relative humidity. Fourteen young healthy adults (8 females) were recruited for this study where they underwent two trials with (Fan) and without an electric fan (No fan) during 50 min of passive heat stress. The skin temperature on forearm and abdomen was lower in Fan than in No fan (all p < 0.02), and the local skin temperature on the chest, and mean skin temperature were significantly lower in Fan than in No fan in the final 20 min (mean value of mean skin temperature: 34.77(0.15) °C vs 35.11(0.12) °C, respectively, all p < 0.03), whilst the rectal temperature was not different between trials (37.11(0.23) °C vs 37.08(0.27) °C, p = 0.78). The sensitivity of local sweat rate (LSR) with the increase of mean body temperature on the chest and forearm was significantly lower in Fan than No fan trials (all p < 0.02). The sum value of thermal sensation was lower and wetness was higher in Fan than in No fan in the final 25 min (thermal sensation: 7.50 (1.25) vs 5.00 (3.06), wetness: −6.57 (2.31) vs −5.21 (2.46), all p <0.03) whilst thermal discomfort did not differ significantly between trials (p = 0.12). The voluntary use of an electric fan attenuates the autonomic thermoeffector response, such as sweating, and influences thermal sensation and wetness but did not affect core temperature and thermal discomfort during lower leg immersion. • Voluntary electric fan utilization reduces skin temperature perceptions and modify heat loss responses during passive heating. • Voluntary electric fan utilizationcould attenuate warmth perception and wetness perception. • Voluntary electric fan utilization does not lower core temperature. [ABSTRACT FROM AUTHOR]

The fan noise in the train electric traction system contributes to the main noise of the train, affecting the comfort of the passengers. The prediction of fan noise can serve as a foundation for the design and fault diagnosis of the fan in the train electric traction system as well as noise reduction. This paper proposes a prediction model based on multiple regression analysis and a double-layer fuzzy neural network (MRA-2LFNN). After the multiple regression analysis of the train electric traction system fan noise is performed to determine the prediction input, a fuzzy neural network is used to predict the fan noise. Afterward, further analysis of noise influencing factors is presented based on the experimental results, and the possibility of the fan optimal design is discussed. This method can make accurate predictions using a small sample of fan noise data, reducing the need for data samples and lowering costs. The experimental results show that the proposed method can achieve better prediction results using the small sample dataset by training and verifying the actual train electric traction system fan noise data, and the average prediction accuracy rate is 94.15%, After discussion, when the number of fan blades is 16, the train electric traction system exhibits improved noise performance. [ABSTRACT FROM AUTHOR]

Jet fans are increasingly preferred over traditional ducted systems as a means of ventilating pollutants in large environments such as underground car parks. The spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)—which causes the novel coronavirus disease—through the jet fans in underground car parks has been considered a matter of key concern. A quantitative understanding of the propagation of respiratory droplets/particles/aerosols containing the virus is important. However, to date, studies have yet to demonstrate viral (e.g., SARS-CoV-2) transmission in underground car parks equipped with jet fans. In this paper, numerical simulation has been performed to assess the effects of jet fans on the spreading of viruses inside underground car parks. [ABSTRACT FROM AUTHOR]

In this study, an innovative system was designed to cool exhaust gases to be used in exhaust gas recirculation (EGR) systems of diesel engines. The designed system uses a 12 V electric pump and fan. PID (Proportional Integral Derivative) controllers are designed for these elements and optimization method is used for the controller parameters. For the amount and temperature of the gases entering the intake manifold, their effects on engine NOx and brake specific fuel consumption (BSFC) under different acclimation conditions were analyzed. A mathematical model was developed using databased methods. The reference EGR flow rate and temperature value for different engine operating conditions have been defined for the control system designed thanks to the obtained mathematical model. The compatibility of models defined with Adaptive Neural Fuzzy Inference System (ANFIS) with real data was statistically analyzed. [ABSTRACT FROM AUTHOR]

Dust masks are widely used to prevent the inhalation of particulate matter into the human respiratory organs in polluted air environments. The filter of a dust mask inherently obstructs the natural respiratory air flows, and this flow resistance is mainly responsible for the discomfort experienced when wearing a dust mask. In atmospheric conditions seriously contaminated with fine dust, it is recommended that common citizens wear a dust mask in their everyday lives, yet many people are reluctant to wear a dust mask owing to the discomfort experienced when wearing it for a long time. Understanding of physical reasons for the discomfort is thus crucial in designing a dust mask, but remains far from clear. This study presents a technique to quantify the wearing comfort of dust masks. By developing a respiration simulator to measure the pressure loss across a dust mask, we assessed the energy costs to overcome flow resistance when breathing through various types of dust masks. The energy cost for a single inhalation varies with the mask type in a range between 0 and 10 mJ. We compared the results with the survey results of 40 people about the wearing comfort of the dust masks, which revealed that the wearing comfort crucially depends on the energy cost required for air inhalation though the dust mask. Using the measured energy cost during inhalation as a parameter to quantify the wearing comfort, we present a comprehensive evaluation of the performance of dust masks in terms of not only the filtering performance but also the wearing comfort. Our study suggests some design principles for dust mask filters, auxiliary electric fans, and check valves. [ABSTRACT FROM AUTHOR]

The vibration parameters of a bi-copter-type unmanned aerial vehicle is optimized by considering operational vibration with payloads. The double electric ducted fan loads, which transmit excitations to the fuselage, are predicted and compared using optimization methods. While the minimum vibration amplitude for stress will be achieved at 7.69 Hz, it will be 9.80 Hz. for minimum deformation without sacrificing safety factor requirement. It ensures sensitive vertical acceleration. It is not seen significant differences on results from screening and genetic algorithm methods. Correlations between frequencies and structural responses are determined. It is observed that the stress and deformation amplitudes of the structure decreases at increasing frequencies up to the next natural frequency. While the highest amplitude is seen at the first frequency, it decreases in increasing modes. The airframe structural model's operational frequency must be 7.69 or 9.80 Hz to achieve sensitive vertical acceleration. Subsequently, it is aimed to develop an autonomous task by the implemented system controlled by various algorithm as a future work. [ABSTRACT FROM AUTHOR]

Failure in the form of stress corrosion cracking has occurred on the SS304 lance tube soot blower. The hardness test showed high value for the area close to the failed region. The SEM test showed formation of heterogonous and porosity film on the surface. XRD indicated that the oxides determined were Fe2O3 and Fe3O4. Metallographic of the lance tube revealed pitting as the stress concentrator. Pitting is caused by chloride (as chlorine) and SO2− from the flue gas. SO2− reacts with water to form acidic sodium bisulfate (NaHSO4). Stress is generated from exposure of lance tube parts to high and low temperature during its service. [ABSTRACT FROM AUTHOR]

Hospitals tend to have high density of occupancy. Poor indoor environmental quality in hospital buildings can exacerbate the health problems of patients and also harm visitors and staff. This study investigated the environmental characteristics and ventilation affecting the concentration of microorganisms in multiple-bed hospital wards. The measurements were accomplished by using a biosampler and an open plate method at four wards, different positions of electric fans, and different times. Data were analyzed by t-test and MANOVA. The results revealed that the concentrations of airborne bacteria were higher than the concentrations of fungi. There were significant differences in the concentrations of bacteria and fungi between sampling times and between hospital wards (p < 0.05), while no difference was observed by positions of electric fans. Correlations between the concentrations and other environmental parameters indicate that temperature, number of occupants, and humidity were physical factors associated with the concentrations of microorganisms. In addition, mostly, Gram-positive bacteria were observed. This indicates the conditions in buildings in the tropical climate, and regular housekeeping of all room areas is needed to prevent the growth of airborne contaminants and the related risks to patients, visitors, and staff. [ABSTRACT FROM AUTHOR]

This paper presents the results of four electromagnetic compatibility (EMC) tests carried out in the anechoic chamber of Universidad de los Andes (Bogotá, Colombia) on mechanical ventilators manufactured by different Colombian initiatives responding to the COVID-19 emergency. The four tests were carried out in accordance with the IEC 60601-1-2 product standard. The tests were the following: radiated immunity in the 80 MHz to 1000 MHz frequency, according to generic standard IEC 61000-4-3; radiated immunity at specific frequencies of 385 MHz, 450 MHz, 710 MHz, 745 MHz, 780 MHz, 810 MHz, 870 MHz and 930 MHz, in accordance with generic standard IEC 61000-4-3; conducted emissions, in accordance with the CISPR 11 standard; and radiated emissions, in accordance with the CISPR 11 standard. It describes the standards used to carry out the tests, the experimental setup used in each test, the observed results and the mitigation measures required to pass the tests. The results are discussed and necessary measures are suggested to promote the development of electromagnetic compatibility in Colombia. [ABSTRACT FROM AUTHOR]

Introduction: The use of carbon dioxide blower has been recognized as the standard of care in patients undergoing beating coronary artery bypass grafting (CABG) due to higher solubility and lower risk of embolization. On the other hand, the compressed air blower has gone out of use since air can be easily trapped and is less soluble which can cause coronary embolism. The present study aimed to compare the outcomes of patients undergoing on-pump beating CABG using CO2, as opposed to an air blower. Materials and Methods: A total number of 125 patients requiring coronary revascularization underwent on-pump beating CABG within February 2017-February 2018. In the current cross sectional study, 45 patients underwent CABG with CO2 blower and other patients were operated using air blower. The reported postoperative outcomes included mortality, low cardiac output state, malignant arrhythmia, postoperative myocardial infarction, blood transfusion, transient ischemic attack or stroke, intra-aortic balloon pump (IABP), as well as intensive care unit and hospital length of stay. Results: Demographic characteristics of patients in two groups in terms of age, sex, risk factors, echocardiographic and angiography data were similar and demonstrated no significant difference. Patients' outcomes, such as cardiac arrhythmias, myocardial infarction, ICU and hospital stays, were also similar in both groups. In addition, the overall morbidity and hospital mortality showed no significant difference between the two groups. Conclusion: Although the use of CO2 during beating CABG has been advocated with its theoretical advantages, no significant difference was observed between the two groups in terms of mortality and morbidity using CO2, as opposed to air blower. [ABSTRACT FROM AUTHOR]

When Martin Luther King, Jr. described the "fierce urgency of now" at 1963s March on Washington, he at once drew upon a shared cultural memory and social consciousness. In a manner as much musical as rhetorical, Dr. King explicated his theme through a series of calls and responses on the riff, "now is the time." When poet and activist Amiri Baraka cited John Coltrane as the "black blower of the now" in his 1979 poem "AM/TRAK," he asserted the saxophonist's contemporary cultural weight more than a decade after his passing. In ways similar to improvised performance, each example leverages the vitality and relevance of a forward-looking emphasis on "the now" against the blurred borders of jazz and spoken word. Coltrane's recording of "Alabama" less than three months after King's legendary speech marked a seminal confluence of journalism, rhetoric, and improvisation. This essay will explore John Coltrane's pivotal if involuntary role in shaping this changed dynamic in black activism and in particular, his incorporation of text as both inspiration and musical device. [ABSTRACT FROM AUTHOR]

In order to master the air flow distribution law in the driving face forced with long duct fan accompanied with short duct exhauster during wall-attached jet dust control, the physical simulation tests were carried out in the laboratory under three conditions: only forced ventilation; both forced fan and dust collector fan opened; forced fan, wall-attached duct and dust collector fan all opened. The results showed that, after wall-attached jet dust control, the air flow distribution in the excavating area of roadway is more uniform than that when only the forced fan is opened, and both the forced fan and the dust collector fan are opened, and the airflow speed distribution uniformity coefficient K 0 at the roadway section 3 m from the excavating face increased from 0.68 and 0.70 to 0.83, with an increase of 15% compared with that when only the forced fan was opened, which could facilitate the control of dust dispersion of driving face, so as to improve the dust removal efficiency of dust collector fan; within the area 15 m from the excavating face, the airflow speed near the excavating face was the maximum when only the forced fan was opened, and both the forced fan and the dust collector fan were opened, and it was gradually decreased with the increase of the distance from the excavating face, but in some positions, it increased first, and then decreased gradually after reaching the maximum at the position 3 m from the excavating face; when the forced fan, the wall-attached duct and the dust collector were all opened, the airflow speed from the air outlet of wall-attached duct to the excavating face changed slightly; when only the forced fan was opened, there was an eddy zone within 8 m in the front of excavating face; when the forced fan, the wall-attached duct and the dust collector fan were all opened, there were two eddy zones within 0–8 m and 8–15 m from the excavating face. Unlabelled Image • The air flow distribution is more uniform by wall-attached jet dust control. • When only the forced fan was opened, there was an eddy zone within 8 m in the front of excavating face. • There were two eddy zones the front of excavating face by all-attached jet dust control. • The wall-attached jet dust control could improve the dust removal efficiency of dust collector fan. [ABSTRACT FROM AUTHOR]

An impeller blower is one of the major aerodynamic noise sources in straw threshing machines. To reduce its aerodynamic noise, it is essential to understand the mechanism of gas-material-coupled unsteady flow causing aerodynamic noise. However, it is difficult to clarify the mechanism through measurement. Therefore, the following topics are studied in this article. First, a full-field transient numerical simulation of the gas and solid particulates' unsteady flow inside the impeller blower was carried out using a dense discrete phase model and a large eddy simulation turbulence model. Second, based on the Ffowcs Williams–Hawkins equation, the aerodynamic noise of the impeller blower of the straw threshing machines was numerically calculated. Finally, the numerical results were verified by aerodynamic noise test. The results indicate that (1) sound pressure level at the inlet of the impeller blower is the highest, mainly at 100 Hz, which is the fundamental frequency of the rotating impeller, while the sound pressure level at the fourth harmonic frequency of 400 Hz is the main source of the outlet. The total sound pressure level at the inlet is greater than that at the outlet. It is concluded that the dipole source of the rotating impeller is the main noise source, which was generated by the interaction of blade with the air and material as the impeller rotated. Also, acoustic attenuation, acoustic resonance, and impact noise of material and machinery play important roles in aerodynamic noise distribution. (2) The test and simulation results show good agreement, so the numerical model of aerodynamic noise is reliable. This study will provide a reference for the structural and acoustic optimization design of impeller blowers and their integration into threshing machines. [ABSTRACT FROM AUTHOR]

Driven by rapid depletion of non-renewable energy resources, emission reduction of combustion engine exhaust, noise reduction and in-efficiency of combustion engine demand and production of electric vehicle has seen a significant growth in recent years. However, when it comes to electrification of the aircraft technology, there are a number of challenges and technological limitations faced by the designer such as vicious weight cycle, in-sufficient energy density and power constraints in batteries. This paper outlines those challenges in design and manufacturing of a manned electric aircraft. Using MATLAB, a mathematical model of the electric aircraft is created considering parameters like power required, battery capacity, battery weight and total weight of the aircraft. Range and endurance of an electric aircraft for different variations in payload or passenger capacity will be determined. This detailed study will give a picture on what is achievable using current technology (battery energy density, combustion free jet propulsion etc.) and what can be achieved based on the limitations in developing a electric ducted fan engines. This paper also outlines design challenges being faced in combustion free jet propulsion namely electric ducted fan engines which is needed for propelling the electric aircraft. This paper is concluded with design recommendations and parameters to be considered during design process for a fully electric aircraft. [ABSTRACT FROM AUTHOR]

The present paper reports on an experimental study performed in a seminar room of the University of Luxembourg in a building of the 1970ies without a major renovation. This lecture room is typical for this building period and has a capacity of 60 seats. It is equipped with a mechanical ventilation system that is normally in operation on workdays for 11 hours a day in semester periods (8:00–19:00h), while windows can be opened manually. A blower‐door test revealed that the room is not airtight. During a year, the ventilation system was shut "on" and "off" in periods of some weeks and the consumed final‐energy was measured, as well as the indoor climate assessed by physical and psychological measurements. For instance, the measured CO2 concentrations are marginally better with the ventilation system „on", which was not perceived in any way by the occupants during the investigations. It was not possible to properly identify the impact of ventilation on the consumed heat‐energy, as the room could not be thermally separated from the rest of the building. But with the system "on", there was a clear increase in consumed primary energy due to the electric consumption of the fans. No relationship between the perceived percentage of dissatisfied and perceived climate could be observed. It is concluded that the typical normal operation modus is questionable for seminar rooms in older buildings with variable occupancy and that a simple shut down or semi‐automatic user‐controlled modus by low‐cost retrofit seems advantageous. [ABSTRACT FROM AUTHOR]

Sonic soot blowers (SSBs) are nondestructive tools to prevent ashes and particle build-up on the surfaces of boilers or other similar instruments. For higher performance, sonic soot cleaners should generate a high level-low frequency sound wave. In this article, the sound generation mechanism in these tools has been modeled. Firstly, the governing equations of the diaphragm and the horn and coupling between them are derived. By linearization, a parametric study is performed to find the optimum design points. Based on the eigenvalue analysis, it is shown that the sound generation in sonic soot cleaners is due to instability of the interaction between the diaphragm and the horn. Moreover, it is found that the sound wave frequency is approximately equal to the lowest fundamental frequency of the horn or diaphragm. Finally, the frequency content of an SSB voice is investigated. [ABSTRACT FROM AUTHOR]

We identified a common and relatively frequent glitch in the light transmittance/reflectance measurement during thermal-optical analysis in the Sunset Laboratory bench top thermal-optical analyzer models. In the instrument studied, the glitch is observed for one in three punch analyses when using the default analysis parameters. The occurrence of this glitch can invalidate the split point and thus the OC and EC fractions and absolute quantities reported. The glitch was observed in data from at least three independent laboratories using different thermal protocols. We describe this glitch as a "discontinuity" (rapid increase or decrease occurring over a few seconds) in the laser transmittance or reflectance which happens relatively frequently and whose behaviour varies in amplitude, timing and direction. We use over 2,200 filter-punch analyses to expose the factors that contribute to the risk of such a discontinuity occurring. We demonstrate that these discontinuities are due to the movement of filter punches within the instrument, and can therefore be minimized by decreasing the blower speed of the instrument and, if possible, by ensuring a tighter fit of the filter punch in its holder (by testing different spoons). The decrease in blower speed has a negligible effect on the measured temperature program during analysis and is the single most effective way to reduce the risk of discontinuity occurrence. We recommend these modifications for all Sunset instruments. [ABSTRACT FROM AUTHOR]

Energy performance contracts (EPC) are types of agreements in which a service provider guarantees that customers' buildings will achieve a specified energy performance (i.e., minimum energy savings) to reduce the risk of their investment in energy efficiency improvements. EPC requires prediction of future energy consumption of the building, at the design stage, before construction or major retrofit. To this end, building energy simulations taking into account all the major energy-using components are performed. In particular, fans can contribute significantly to the total building consumption. The overall efficiency of fans is the combination of three factors: mechanical, motor, and variable frequency drive (VFD). Manufacturers usually provide fan mechanical efficiency curves for a broad operating range. In contrast, motor and VFD efficiencies are generally given at rating conditions only. To represent part-load conditions, correlations are typically used to estimate motor and VFD efficiency variations, to evaluate the overall electricity consumption. The first aim of this study is to evaluate existing correlations for motor and VFD efficiency as a function of load and speed, by comparison with manufacturer data, for a vendor that has shared its detailed test data. While VFD efficiency correlations from the literature provide reasonable accuracy against real data, motor correlations under predict actual motor efficiency at low loads. The second aim of the paper is to improve such correlations using Bayesian inference to fit the available data. [ABSTRACT FROM AUTHOR]