Saturation Efficiency Research Articles

Effects of Throughfall Exclusion on Photosynthetic Traits in Mature Japanese Cedar (Cryptomeria japonica (L. f.) D. Don.)

As climate change progresses, it is becoming more crucial to understand how timber species respond to increased drought frequency and severity. Photosynthetic traits in a 40-year-old clonal Japanese cedar (Cryptomeria japonica) plantation were assessed under artificial drought stress using a roof to exclude rainfall and a control with no exclusion. C. japonica is a commercial tree that is native to Japan and has high growth on mesic sites. The maximum carboxylation rate (Vcmax), maximum electron transfer rate (Jmax), and dark respiration rate (Rd) in current-year shoots in the upper canopy were determined from spring to autumn over two growing seasons. In addition, the photosynthetic rate at light saturation (Pmax), stomatal conductance (gs), and intrinsic water use efficiency (WUEi) were measured in the morning and afternoon during the same period. Leaf mass per unit area (LMA) and nitrogen concentration (N) were also measured. The values of Vcmax, Jmax, Rd, N, and LMA did not differ between the two plots. By contrast, significantly lower Pmax and gs and higher WUEi were found in the drought plot, and the reduction in Pmax was accompanied by low gs values. Midday depressions in Pmax and gs were more pronounced in the drought plot relative to the control and were related to higher WUEi. Under drought conditions, mature Japanese cedar experienced little change in photosynthetic capacity, foliar N, or LMA, but they did tend to close the stomata to regulate transpiration, thus avoiding drought-induced damage to the photosynthetic machinery and improving WUEi.

Predicting the critical gradient of ITG turbulence in fusion plasmas

The quasilinear mixing-length approach to efficient prediction of transport in fusion devices is improved to account for the ‘Dimits’ upshift between linear and nonlinear critical pressure gradients in zonal-flow-saturated turbulence regimes. This modification uses the frequency mismatch between modes interacting turbulently to track changes in saturation efficiency. Near criticality, energy is transferred exclusively to stable eigenmodes, rapidly increasing the efficacy of the nonlinearity. The modified quasilinear model is able to predict below-threshold turbulent ion-temperature-gradient-driven transport accurately and also yields significantly improved predictions for trapped-electron-mode transport.

A reservoir quality evaluation approach for tight sandstone reservoirs based on the gray correlation algorithm: A case study of the Chang 6 layer in the W area of the as oilfield, Ordos Basin

As an important type of unconventional hydrocarbon, tight sandstone oil has great present and future resource potential. Reservoir quality evaluation is the basis of tight sandstone oil development. A comprehensive evaluation approach based on the gray correlation algorithm is established to effectively assess tight sandstone reservoir quality. Seven tight sandstone samples from the Chang 6 reservoir in the W area of the AS oilfield in the Ordos Basin are employed. First, the petrological and physical characteristics of the study area reservoir are briefly discussed through thin section observations, electron microscopy analysis, core physical property tests, and whole-rock and clay mineral content experiments. Second, the pore type, throat type and pore and throat combination characteristics are described from casting thin sections and scanning electron microscopy. Third, high-pressure mercury injection and nitrogen adsorption experiments are optimized to evaluate the characteristic parameters of pore throat distribution, micro- and nanopore throat frequency, permeability contribution and volume continuous distribution characteristics to quantitatively characterize the reservoir micro- and nanopores and throats. Then, the effective pore throat frequency specific gravity parameter of movable oil and the irreducible oil pore throat volume specific gravity parameter are introduced and combined with the reservoir physical properties, multipoint Brunauer-Emmett-Teller (BET) specific surface area, displacement pressure, maximum mercury saturation and mercury withdrawal efficiency parameters as the basic parameters for evaluation of tight sandstone reservoir quality. Finally, the weight coefficient of each parameter is calculated by the gray correlation method, and a reservoir comprehensive evaluation indicator (RCEI) is designed. The results show that the study area is dominated by types II and III tight sandstone reservoirs. In addition, the research method in this paper can be further extended to the evaluation of shale gas and other unconventional reservoirs after appropriate modification.

Efficient Highly Subsonic Turbulent Dynamo and Growth of Primordial Magnetic Fields.

We present the first study on the amplification of magnetic fields by the turbulent dynamo in the highly subsonic regime, with Mach numbers ranging from 10^{-3} to 0.4. We find that for the lower Mach numbers the saturation efficiency of the dynamo (E_{mag}/E_{kin})_{sat} increases as the Mach number decreases. Even in the case when injection of energy is purely through longitudinal forcing modes, (E_{mag}/E_{kin})_{sat}≳10^{-2} at a Mach number of 10^{-3}. We apply our results to magnetic field amplification in the early Universe and predict that a turbulent dynamo can amplify primordial magnetic fields to ≳10^{-16} G on scales up to 0.1pc and ≳10^{-13} G on scales up to 100pc. This produces fields compatible with lower limits of the intergalactic magnetic field inferred from blazar γ-ray observations.

Saturation efficiency for detecting 1550 nm photons with a 2 × 2 array of Mo0.8Si0.2 nanowires at 2.2 K

Amorphous materials are attractive candidates for fabricating the superconducting nanowire single-photon detectors (SNSPDs) due to their superior tolerance and scalability over crystalline niobium nitride. However, the reduced superconducting transition temperature degenerates both operating temperature and saturation efficiency. Herein, the SNSPD (6.5 nm thickness and 50 nm width) based on the amorphous Mo 0.8 Si 0.2 film with a high optical absorption coefficient demonstrates close-to-unity intrinsic detection efficiency for 1550 nm photons from 75 mK to 2.2 K. Further, a high-performance array SNSPD with optimized 90 nm-width wires is also demonstrated. As-fabricated uniform 4-pixel SNSPD exhibits a saturation plateau for the photon counts at 2.2 K, which overcomes the limitation of operation at low temperature ( < 1 K ) for traditional amorphous SNSPDs. Coupled with superior intrinsic quantum efficiency, highly efficient photon counts, and low dark count ratio, this detector paves a way for achieving high efficiency and superior yield for large array systems.

Determination of water loss for an adiabatic cooling of a fin fan water cooler

Evaporative coolers are suitable where summer is hot and dry. The evaporative pad made from cellulose material reduces the condensation temperature and improve the specific cooling power of an air cooled condenser. Water is needed in the adiabatic cooler to cool the fresh hot outside air and to reduce the condensing temperature. The cooler manufacturing companies as well as the customers should be aware about the water loss throughout the year for a particular cooler. In this paper, the main intention is to determine the water loss for the specific fin fan cooler. When the pads are wetted, temperature of air decreases which results into cooling and humidified air. The water losses are estimated with the weather data for different pad materials. Due to the scale formation in evaporative condenser, pressure drop increases and pad saturation efficiency decreases. It is estimated that 5.2 L per hour water consumption is needed for the fin fan cooler studied at dry bulb temperature of air at 38 °C in summer condition.

Pregled zajedničkih sistema prirodne ventilacije i hlađenja isparavanjem za staklenike i realnost Nigerije

Greenhouses simulate the "desired" environment for successful growth and development of plants. They, by design, achieve this desired environment by supplying the necessary climatic inputs needed by the plants to strive and at the same time exclude factors impeding the growth of plants, hence it is called a controlled environment. One of the common and most desired attribute of the greenhouse is its ability to provide effective cooling to the plants. This paper reviewed, extensively, the concept of evaporative cooling as applied in greenhouses. Factors like Vapor Pressure deficit (VPD), Relative Humidity, Ambient Temperature were also discussed with regards to its effects on the efficiency of the evaporative cooling system. The efficiencies of the Fan and Pad System and the Fog systems were reviewed and compared with their consequent dependence on factors like nozzle spacing, nozzle length, saturation efficiency of pad material etc. The Natural Ventilation method was also reviewed as a "stand alone " greenhouse cooling method and as an augmentation to other cooling systems. Factors like rate of air exchange, total area of vents, wind speed, vent opening angles etc. were also discussed in line with their effects on the effectiveness of the Natural ventilation method. The Nigerian Perspective on Greenhouses and its Cooling methods was also discussed with reference to local development of evaporative coolers as well as its importation, its affordability, management, availability and appliance to the Nigerian farming culture.

Effect of pad water flow rate on evaporative cooling system efficiency in laying hen housing

An experiment was conducted in three commercial laying hen houses with 32-week-old hens in the summer of 2017 in a commercial farm in Gharbia Province, Egypt (31.06ºN, 31.16ºE) using an evaporative pad cooling system to determine the most suitable water flow rate for maintaining indoor air temperature within the thermal comfort zone. The experiment was conducted using three different water flow rates, i.e. 4.76, 5.65, and 6.35 L min–1.m–2, to assess the effect of different water flow rates on evaporative pad cooling system performance and determine the most suitable water flow rate for maintaining the thermal comfort zone of laying hens. The evaporative pad cooling system maintained the mean indoor air temperature below 28°C. The mean indoor air relative humidity during the experimental period ranged from 72.6 to 73.8%. The 4.76 L min–1.m–2 water flow rate resulted in the highest saturation efficiency (ca. 73.75%). In contrast, the 6.35 L min–1 m–2 water flow rate resulted in the lowest saturation efficiency (70.63%). The mean cooling energy values were 69.11, 66.0, and 66.65 kwh for water flow rates of 4.76, 5.56, and 6.35 Lmin–1m–2, respectively. The highest temperature-humidity index was 27.78°C, which indicated that birds were not stressed in all treatments.

Design of 74% Fractional Bandwidth Continuous-Mode Doherty Power Amplifier Using Compensation Susceptance

This brief presents a novel design method of broadband continuous-mode Doherty power amplifier (CM-DPA) using compensation susceptance. In particular, at power back-off point, the compensation susceptance is added at the current source plane of the carrier PA to make it operates in continuous mode, which thus enhances the back-off efficiency and extends the bandwidth. Meanwhile, considering the influence of the parasitic parameters of the PA in practical design, the designed compensation susceptance at the current source plane is equivalently transformed into the compensation susceptance at the package plane of the carrier PA. Additionally, at saturation point, the load impedances at the package plane of both carrier and peaking PAs can meet the impedance conditions of drain efficiency more than 60%. Based on the proposed method, a 74% fractional bandwidth CM-DPA operating from 1.1 to 2.4 GHz is designed and measured. Under the continuous-wave excitation, the measured 6-dB back-off efficiency is 46.8%-63% and the saturation efficiency is 59.1%-78.8%. The measured small-signal gain and back-off gain are 10-12 dB and 9.1-10 dB, respectively.

Development of an evaporative cooler system applied to the air conditioning of urban buses

Air conditioning for buses is an important incentive tool for the public transport, since it offers comfort to passengers and stimulates the use of this kind of transport which is fundamental to improve urban mobility. Currently, air conditioning equipment for buses is the mechanical vapor compression (MVC) type. However, this kind of system has two main disadvantages: the high financial cost and power consumption by the vehicle engine. The purpose of this study is to develop an evaporative cooler for buses, which is a simple, environmental friendly, low-cost solution that does not use engine power for its operation. The first step was the design and construction of the prototype. The following step was to evaluate the built prototype through performing experimental tests. The prototype presented a saturation efficiency of approximately 70%, airflow rate of 421.5 m³/h and energy consumption of 98.4 W. After determining the prototype technical characteristics, the evaporative cooling system was developed for an urban bus, seeking to meet the air renewal required by ANSI/ASHRAE standard 62.1 and to promote the passenger’s thermal comfort as specified by ISO 7730 and ANSI/ASHRAE Standard 55. The thermal comfort provided by the new cooling system was evaluated through the PMV-PPD indexes. A value of 0.35 was obtained for the PMV index and the PPD index obtained a value of 7, indicating that approximately 93% of the passengers will be satisfied regarding their thermal comfort for the established environmental conditions. The evaporative cooling system had a total energy consumption of approximately 0.4 kW, which represents only 5% of the energy that would be consumed by a MVC system. Therefore, the evaporative cooling performance depends on the climatic conditions of the environment, especially humidity. However, when applied in favorable conditions (low humidity), the evaporative cooling system proved to be a viable solution to replace the MVC systems in buses air-conditioning application, where its main advantage is its positive cost-benefit and energy savings. http://dx.doi.org/10.18226/23185279.v8iss1p46

Optimizing carrier balance of a red quantum-dot light-emitting electrochemical cell with a carrier injection layer of cationic Ir(III) complex

Abstract Solid-state light-emitting electrochemical cells (LECs) with promising features of solution processability, low-voltage operation and compatibility with inert cathode metals have shown great potential in display and lighting applications in recent years. Among the reported emissive materials for LECs, ionic transition metal complexes (iTMCs) have relatively higher electroluminescence (EL) efficiencies due to their phosphorescent property. However, the red iTMCs generally exhibit moderate color saturation and low emission efficiency, limiting their display applications. To improve color saturation and device efficiency of red LECs, efficient quantum dots (QDs) with narrow emission bandwidth are good alternative emissive materials. In this work, efficient and saturated red QD LECs employing iTMC carrier injection layers to provide in situ electrochemical doping are demonstrated. The thicknesses of iTMC and red-QD layers are systematically adjusted to achieve the best carrier balance. In the optimized device, the iTMC carrier injection layer facilitates hole injection into the red-QD layer while electrons are injected from the cathode into the red-QD layer directly since the electron injection barrier is low. The Commission Internationale de I'Eclairage (CIE) coordinates of the EL spectra approach the red standard point of National Television System Committee (NTSC). High external quantum efficiency and current efficiency reaching 9.7% and 16.1 cd A−1, respectively. These results confirm superior carrier balance in such a simple iTMC/QD bilayer device structure. Furthermore, compared with iTMC LECs, less degree of device efficiency roll-off upon increasing device current is observed in QD LECs since a shorter excited-state lifetime of fluorescent QDs reduces the probability of collision exciton quenching. Saturated and efficient red EL with mitigated efficiency roll-off from red-QD LECs employing iTMC carrier injection layers confirms that they are good candidates of saturated light sources for displays.

REDUCE ENERGY AND HEAT STRESS IN CLOSED RABBIT HOUSING UNDER EGYPTIAN DELTA ZONE CONDITIONS

Many rabbit housing in Egypt were constructed without systematic design models from the viewpoint of sizing evaporative pad cooling system were determined by subtle mathematical models to solve this problem. Four commercial rabbit houses located at 30.95°N and 31.09°E and the pad fan evaporative cooling system were used to reduce the energy and side effects of heat stress on rabbit housing during summer 2017. Three different mathematical forms these forms were ASHRAE form (form 1); airflow depended upon the volume of the house (form 2), and heat balance (from 3). The house that operated with pad fan evaporative cooling and full pad area facing the fan had the best conditions for rabbits and the highest values of cooling performance. Therefore, the actual results for the previous house were the lowest indoor temperature was 26.85°C, the highest indoor relative humidity was 67.83 %, the highest saturation efficiency of cooling was 76.28%, the highest cooling potential was 7.25 °C and the highest value of the temperature-humidity index was 25.6 °C. Finally, when compared the obtained results from these houses with the results from calculation models, can found that these houses related nearly with the heat balance model.

Assessment of direct evaporative cooler performance with a cooling pad made from banana midrib and ramie fiber

PurposeThe paper aims to apply Buckingham Pi dimensional analysis method for assessing direct evaporative cooler performance with a cooling pad made of banana midrib and ramie fiber. The saturation efficiency acted as the indicator performance of the evaporative cooler.Design/methodology/approachThe paper describes an experimental study of the direct evaporative cooler with a cooling pad made of banana midrib and rami fiber. There were six parameters in the experiment: absorbed water as a dependent variable was affected by independent parameters such as air velocity and temperature, cooling pad cross-section area and thickness. Based on these variables, we arranged three dimensionless numbers and their correlation.FindingsThe paper provides three calculated dimensionless numbers plotted on a curve with a specific correlation. The curve trends for 30 mm and 50 mm pad thickness were almost similar. The range of Reynolds number for 10 mm pad was narrower than other pad thicknesses. The thicker the cooling pad, the more extensive was the calculated Reynolds number range. A new curve exhibited the relationship between the evaporation rate with the μA/t number. The broader cooling pad cross-section, the thinner pad thickness, and the lower pad temperature were factors that increased the evaporation rate, even though the increase was less significant.Originality/valueA new material in cooling pad from banana midrib fiber was tested and compared to ramie fiber and conventional cooling pad.

A novel sequence to improve auditory functional MRI with variable silent delays.

Auditory functional MRI (fMRI) often uses silent inter-volume delays for stimulus presentation. However, maintaining the steady-state of the magnetization usually requires constant delays. Here, a novel acquisition scheme dubbed "pre-Saturated EPI using Multiple delays in Steady-state" (SEPIMS) is proposed, using spin saturation at a fixed delay before each volume to maintain steady-state conditions, independent of previous spin history. This concept allows for variable inter-volume delays and thus for flexible stimulus design in auditory fMRI. The purpose was to compare the signal stability of SEPIMS and conventional sparse EPI (CS-EPI). The saturation module comprises two non-selective adiabatic saturation pulses. The efficiency of the saturation and its effect on the SEPIMS signal stability is tested in vitro and in vivo. Data show that SEPIMS yields the same signal stability as CS-EPI, even for extreme variations between inter-volume delay durations. However, dual saturation pulses are required to achieve sufficiently high saturation efficiency in compartments with long T1 values. Importantly, spoiler gradient pulses after the EPI readout have to be optimized to avoid eddy-current-induced image distortions. The proposed SEPIMS sequence maintains high signal stability in the presence of variable inter-volume durations, thus allowing for flexible stimulus design.

Study of the Cardiorespirator System Response to Normobaric Hypoxia

Research into cardiorespiratory responses to prolonged hypoxia (more than 60 minutes) is of particular interest in terms of elucidating adaptive mechanisms under the conditions of oxygen deficiency. Aim: to identify the parameters of the cardiorespiratory system under relative rest most sensitive to hypoxia and to determine the most optimal time interval for a hypoxic test. Experiments were carried out in a normobaric hypoxic complex, in which hypoxic respiratory gas conditions were created corresponding to the partial oxygen pressure at altitudes of 3500 and 4500 m. Cardiorespiratory responses were evaluated using a MetaLyzer 3B ergospirometric system (Cortex, Germany). Indicators sensitive to moderate normobaric hypoxia under relative rest include hemoglobin oxygen saturation (the most sensitive indicator), oxygen and carbon dioxide ventilation efficiency (VE/VO 2 and VE/VCO 2 ), respiratory rate and respiratory coefficient (VCO 2 / VO 2 ). A significant change in the indicators of the cardiorespiratory system at an altitude of 4500 m was noted within 5 minutes following hypoxic exposure; therefore, normobaric hypoxic tests should be carried out at this height under the hypoxic exposure of 30 minutes.

Experimental Investigation of the Potential of a New Fabric-Based Evaporative Cooling Pad

Direct evaporative coolers are energy-efficient, economic solutions to supplying cooling demand for space conditioning. Since their potential strongly depends on air hygrothermal conditions, they are traditionally used in dry and hot climates, though they can be used in many applications and climates. This work proposes a new direct evaporative cooling system with a fabric-based pad. Its design enables maximum wetted surface with minimum pressure drop. Its performance has been experimentally characterized in terms of saturation efficiency, air humidification, pressure drop, and level of particles, based on a full factorial Design of Experiments. Factors studied are air dry bulb temperature, specific humidity, and airflow. Saturation efficiencies obtained for a 25 cm pad are above the values achieved by other alternative evaporative cooling (EC) pads proposed in the literature, with lower pressure drops.

Assessing the variable performance of fan-and-pad cooling in a subtropical desert greenhouse

The cooling performance of a fan and pad system applied in a subtropical desert greenhouse (in Ahvaz-Iran) was evaluated during the critical climatic period from May to October using validated Computational Fluid Dynamics (CFD) method. The boundary and initial conditions of the models were set based on regional meteorological reports. Pad was separately simulated inside a wind tunnel and the porous media properties were extracted and applied in the greenhouse model. Transient fan and pad saturation efficiency, indoor temperature and its homogeneity in comparing to natural ventilation were considered for this evaluation. The regional meteorological reports, as well as physical experiments, approved the accuracy of the CFD models. 15–25 °C temperature reduction with a higher temperature heterogeneity was observed at the crop region in comparing with naturally ventilated from May to October. A transient fan and pad saturation efficiency from 57% to 77% was observed during the warmest day of the year (16 July 2019). Comparing indoor microclimate at the solar noon during the critical period of the year, showed a variable fan and pad saturation efficiency from 58% to 75% due to the variable solar heat load and dynamic seasonal climatic conditions.

Experimental investigation of a U-tube thermocell under various Fe(CN)63−/4− concentration

Research interest in thermocell technology has been increasingly occurring due to its large Seebeck coefficient (~1 mV/K) and flexible structure, which are its unique advantages for use in wearable devices directly converting thermal energy into electricity. It is timely and critical to investigate the technology to potentially overcome the technological drawbacks of thermocell such as its relatively low power density and limited overall energy efficiency. In this paper, the correlation between the performance of a Fe(CN)63−/4− thermocell and ion concentrations are studied through factorial experiments. Solubility tests are conducted to obtain the maximum concentration. Activity coefficient is found non-negligible in the Nernst equation. The saturation line calculated through concentration solubility product shows relatively close agreement with experimental results. Total concentration, as well as the concentration ratio of ions, have a significant effect on the thermocell performance. At the optimised concentration point on the saturation line, power density, Seebeck coefficient and efficiency respectively increase by 7.38%, 8.93% and 5.69%. And the mass of solute decreases by 12.64%, compared with the widely used 1:1 concentration ratio. Results demonstrate to improve the power density of thermocell, the solution needs to be saturated and the ion concentration ratio should be taken into account.

Simulation-based performance analysis of residential direct evaporative coolers in four climate regions of Iran

In this paper, the effect of direct evaporative cooling (DEC) system design parameters, including the cooling pad saturation efficiency, the airflow rate, and the thermostat set-points on the system electricity and water consumption, is evaluated in four different climates of Iran according to Köppen-Geiger classification. EnergyPlus is used to perform the simulations for a typical residential apartment. The results show that using pads with a 30% higher saturation efficiency can significantly decrease the electricity and water consumption by up to 50.0% and 29.6%, respectively, because of the working time reduction. The maximum impact is in Esfahan city in cold desert climate as its wet-bulb temperature is lower than other investigated climates. Besides, increasing the airflow rate from 3000 m3/h to 6000 m3/h leads to 43.4%–55.2% reduction in electricity consumption in different climates, although the water consumption increases by 20.5%–58.8%. According to the results, by using the DEC system with 80% saturation efficiency and 6000 m3/h airflow rate, the average indoor relative humidity and CO2 concentration is 42.3%–48.5%, and 450 ppm–470 ppm, respectively, in different climates, which can provide acceptable indoor air quality. Increasing the saturation efficiency or decreasing the airflow rate increases the indoor relative humidity and CO2 concentration. The results are also compared with a typical packaged terminal air conditioner (PTAC). The total hours when the indoor relative humidity is out of comfort zone in the DEC system, with 60% saturation efficiency, are about 92% lower than the PTAC system, on average. Moreover, with 24/26 °C thermostat set-points, the PTAC system consumes 234%–265% more electricity than the DEC one with 80% saturation efficiency in different climates.

A K-Band Frequency Tripler Using Transformer-Based Self-Mixing Topology With Peaking Inductor

This article presents a K-band frequency tripler with bandwidth enhancement techniques. A transformer-based self-mixing topology with peaking inductor (TSM-PI) is introduced to settle the drawbacks in DC distortion, bandwidth, and output voltage of the conventional self-mixing structure. Theoretical analyses compared with the conventional one are proposed, which shows the TSM-PI structure improves performances significantly. With these techniques, a K-band ultrawideband frequency tripler is designed and implemented in a 0.11-μm complementary metal oxide semiconductor (CMOS) process. It achieves a 50.6% fractional bandwidth from 17.7 to 29.7 GHz. With a very low-power consumption of 7.2 mW, the saturation output power and efficiency are 0.28 dBm and 15.2%, respectively.