Short Air Research Articles

Optimization of thermal environment and airflow distribution in data center with row-based cooling using the Taguchi/TOPSIS method

The short air supply distance of the row-based cooling system improved the cooling efficiency. However, the row-based coolers are closer to the racks, resulting in high-speed airflow and airflow mixing problem in the aisles. The internal structure of a row-cooled cluster is closely related to the cooling effect, and existing studies neglect the synergistic effect of multiple factors on the thermal performance of the row-based cooling system, which is still controversial about the optimal form of a row-based cooling cluster. This study analyzes and presents row-based cooling system airflow problems through large-scale field experiments and simulation. All rows' supply heat index (SHI) exceeds 0.2, and the return temperature index (RTI) exceeds 100 %, indicating a poor thermal environment in the DC. Taguchi and TOPSIS methods were used to analyze the coupling effect on the number of racks, power density, hot and cold aisle width, cooler's location, server's location, and blanking panels of the cluster's thermal environment. The optimal row-based cooling cluster structure form for different rack numbers and power density was determined. In order to optimize the air supply path of the cooler to reduce the air supply stream's collision, the effects of deflectors with different structures installed at the cooler supply and return air vents on the thermal environment were analyzed based on the optimal cluster structure. In practice, it is recommended to install deflectors of 45° with 50 mm, 75° with 30 mm, or 70 mm in the air supply vent of the cooler to create a better thermal environment. After cluster and deflector optimization, temperature uniformity, vortex airflow, and hot spots in the cluster are improved. SHI, RTI, and standard deviation of each cluster's average inlet air temperature are all closer to the ideal values.

Heat Enhancement in a Short Air Channel with Solid and Permeable Baffles

Heat transfer enhancement to turbulent air flow in a short rectangular constant-wall temperature channel fitted with either solid or permeable baffles were numerically studied based on COMSOL® simulations. The number of used baffles (1 to 7), Reynolds number (10000, 20000, and 30000), and baffle permeability (1 × 10−11 to 1 × 10−6) were investigated. Operations under turbulent flow conditions were considered, which has not been extensively studied. The average temperature of air at the channel exit and the pressure drop along the channel were obtained via simulation for different cases. For solid baffles, the heat transfer enhancement parameter ranged from 0.30 to 0.35 due to the high friction, while for permeable baffles, it ranged from 1 to 35 as the permeability and number of baffles increased. This is due to the heat-transfer-area increase and pressure-drop reduction when the flow passes through the permeable baffles. For permeable baffles, a minimum heat exchanger temperature approach of 10 K was achieved with minimal pressure drop at a permeability of approximately 4 × 10−8 when using 4–6 permeable baffles. Accordingly, the results demonstrated that using four permeable baffles with a permeability of approximately 4 × 10−8 m 2 is optimal from thermal, economical, and mechanical viewpoints.

Ultra-high temporal resolution images of a homogeneous electric field short air gap negative streamer at overvoltage and atmospheric pressure

Air gap discharge is one of the most basic scientific problems in the field of high-voltage engineering. The homogeneous electric field 1.5 mm air gap negative streamer at overvoltage and atmospheric pressure is observed by a high-speed 4-channel framing camera. The ultra-high temporal resolution images of a single negative stream are captured (the exposure time is 5 ns, and the inter-frame delay is no more than 0.1 ns). It is observed that the negative streamer formed in the middle of the air gap and grew bidirectionally towards both electrodes. At the same time, the electrical measurement is also carried out.

Starch powder in short air contact time: Material moisture change, stickiness and deposition at different air relative humidity and temperature

Starch powder can get sticky and cause deposition in process, resulting in downtime and performance deterioration. Glass transition temperature (Tg) is a key aspect of semi-crystalline material stickiness, being function of material water content, and the surpass of material temperature above Tg is related to its stickiness. During pneumatic transport and process, in short air contact time, powders can exchange heat and water, which might change stickiness. Dairy powders were already assessed on stickiness tests replicating these conditions, but not starches. Potato and corn starch powders are investigated and stickiness, deposition and water content change are measured. Water content changed linearly with relative humidity. Deposition occurred on a plate at high and low air flow velocities and the deposition patterns correlate with the flow velocity profile. Corn starch presented higher stickiness and more deposition. Stickiness can be achieved by the combination of different air temperatures and relative humidities.

Phase unwrapping for MHz optical coherence elastography and application to brain tumor tissue.

During neuro-oncologic surgery, phase-sensitive optical coherence elastography (OCE) can be valuable for distinguishing between healthy and diseased tissue. However, the phase unwrapping process required to retrieve the original phase signal is a challenging and critical task. To address this issue, we demonstrate a one-dimensional unwrapping algorithm that recovers the phase signal from a 3.2 MHz OCE system. With a processing time of approximately 0.11 s per frame on the GPU, multiple 2π wraps are detected and corrected. By utilizing this approach, exact and reproducible information on tissue deformation can be obtained with pixel accuracy over the entire acquisition time. Measurements of brain tumor-mimicking phantoms and human ex vivo brain tumor samples verified the algorithm's reliability. The tissue samples were subjected to a 200 ms short air pulse. A correlation with histological findings confirmed the algorithm's dependability.

Assessment of waste workers occupational risk to microbial agents and cytotoxic effects of mixed contaminants present in the air of waste truck cabin and ventilation filters

ABSTRACT Workers in the waste-processing industry are potentially exposed to high concentrations of biological contaminants, leading to respiratory and digestive problems and skin irritations. However, few data on the exposure of waste collection truck (WCT) drivers are available. The goal was to document the microbial risk of the waste collection truck (WCT) workers while in the vehicle cab. Long-period sampling using the truck air filters (CAF) and short time ambient air sampling in the cab were used. The potential release of microbial particles from CAFs was also investigated since it could contribute to the microbial load of the cabin air. A combination of analytical methods also helped assess the complex mixture of the biological agents. Aspergillus sections Fumigati and Flavi, E. coli, Enterobacter spp. and Legionella spp. were detected in the CAF of trucks collecting three types of waste. The highest levels of bacteria and fungi were found in the CAF from organic WCT. The highest endotoxin concentrations in CAF were 300 EU/cm2. Most of the CAF showed cytotoxic effects on both lung cells and hepatocytes. Only one mycotoxin was detected in a CAF. The maximal concentrations in the ambient WCT air varied according to the type of waste collected. The highest proportion (84%) of the air samples without cytotoxic effects on the lungs cells was for the recyclable material WCTs. The results revealed the potential microbial risk to workers from a complex mixture of bio-contaminants in the cabs of vehicles collecting all types of waste. The sustained cytotoxic effect indicates the potential adverse health-related impact of mixed contaminants (biological and non-biological) for the workers. Overall, this study highlights the benefits of using complementary sampling strategy and combined analytical methods for a the assessment of the microbial risk in work environments and the need to implement protective measures for the workers. Implications: Exposure to microbial agents is a well-known occupational hazard in the waste management sector. No previous study had evaluated the cytotoxicity of ambient air and ventilation filters to document worker exposure to a combination of contaminants during waste collection. This research confirms the usefulness of ventilation filters for long-term characterization of exposure to infectious agents, azole-resistant fungi, coliform bacteria and mycotoxin. Overall, this study highlights the importance of using several sampling and analysis methods for a comprehensive assessment of microbial risk in work environments, as well as the need to implement appropriate protective measures for collection workers.

Increased Risk for Hospitalization Associated with Short Term Particle Air Pollution Exposure for California Residents with Sickle Cell Disease

Background: Air pollution is associated with numerous adverse health outcomes in the general population such as asthma exacerbations, pneumonia, myocardial infarction, and stroke. There is a strong association between air pollution and mechanistic processes associated with oxidative stress, vasoconstriction, and inflammation, suggesting a high risk of exposure for those with sickle cell disease (SCD). A small number of published studies have explored this relationship, primarily focusing on children. Only two studies have examined air pollution in the US, both with outcomes among urban area hospitals in Atlanta, GA. None have taken place in California, which has the worst air quality, including the four most polluted cities in year-round particle pollution in the nation. Additionally, all published studies have overlooked more rural exposure areas. Recent advances in environmental exposure assessment have enabled high-resolution predictions of ambient air pollution concentrations in the whole US, making it possible to cover unmonitored suburban and rural areas that were unrepresented in the past. In addition, these high-resolution predictions are more precise surrogates of the personal exposure measures than monitored data. Particulate matter with a diameter of 2.5 microns or less (PM 2.5) is the most harmful pollutant based on current research findings. We hypothesized that short term increases in PM 2.5 exposure were associated with an increased risk for hospitalization among individuals with SCD in California. Methods: We designed a time-stratified case-crossover study to estimate the percent change in risk for hospitalization for SCD complications associated with each 1mg/m 3 increase in PM 2.5 exposure. The zip code of residence was used to spatially link each hospital admission with PM 2.5 exposure using a novel hybrid exposure model allowing for estimated exposure in areas without direct remote sensing. We used conditional logistic regressions to examine the PM 2.5 exposures at 7-day moving average and single lag days (from lag 0 to 6 days) before admission, adjusting for nonlinear confounding effects of air temperature and humidity at the same exposure window. We examined risk for all hospitalizations and specifically for vaso-occlusive pain (VOC) and acute chest syndrome (ACS). Results: From 2000-2016, among 5,835 California residents with SCD, there were 107,450 admissions for sickle cell disease complications with VOC being the most common indication (71.1%). PM 2.5 air pollution data was examined among 2,634 zip codes throughout the state. Residents with SCD were noted to be living among 1,180 zip codes. The daily burden of PM 2.5 was higher in zip codes with residents with SCD (mean 11.5 mg/m 3, standard deviation [SD] 9.0) when compared to zip codes without residents known to have SCD (mean 9.2 mg/m 3, SD 8.6, p<0.001) ( Table 1). Overall, the mean daily burden of PM 2.5 declined in the period of 2010-2016 when compared to that from 2000-2009. However, the daily mean PM 2.5 concentration remained higher in zip codes with individuals with SCD. No significant association was seen in examining the week-long exposure to PM 2.5 and increase risk in hospitalizations for any indication over the entire study period (2000-2016). However, when examining the more contemporary period of 2010-2016, we identified that each 1mg/m 3 increase in PM 2.5 was associated with 0.22% increased risk for SCD hospitalization (Confidence Interval [CI] 0.02-0.42, p=0.03) 3 days prior to admission. We observed a 0.26% increased risk for hospitalization for VOC with each 1 mg/m 3 increase in PM 2.5 exposure (CI 0.02-0.49, p=0.03) at lag day 3 (Figure 1). No effect was seen with PM 2.5 on hospitalizations for ACS during any time period. Discussion: Our study suggests that short term air pollution exposure may be a trigger for hospitalization for individuals with SCD. In particular this effect is seen in the more recent years with a lower daily average PM 2.5 burden overall, suggesting attention may be needed well below Environmental Protection Agency (EPA) thresholds. Consistent with previous studies, lag day 3 PM 2.5 exposure is associated with an increased risk for hospitalization for VOC. These results may have important implications in understanding risk factors for hospitalization for children and adults with SCD.

WASP: Wearable Analytical Skin Probe for Dynamic Monitoring of Transepidermal Water Loss.

Early diagnosis of skin barrier dysfunction helps provide timely preventive care against diseases such as atopic dermatitis, psoriasis, food allergies, and other atopic skin disorders. Skin barrier function is commonly evaluated by measuring the transepidermal water loss (TEWL) through stratum corneum due to its noninvasive characteristics. However, existing commercial TEWL devices are significantly affected by many factors, such as ambient temperature, humidity, air flow, water accumulation, initial water contents on the skin surface, bulky sizes, high costs, and requirements for well-controlled environments. Here, we developed a wearable closed-chamber hygrometer-based TEWL device (Wearable Analytical Skin Probe, WASP) and the related algorithm for accurate and continuous monitoring of skin water vapor flux. The WASP uses short dry air purges to dry the skin surface and chamber before each water vapor flux measurement. Its design ensures a highly controlled local environment, such as consistent initial dry conditions for the skin surface and the chamber. We further applied WASP to measure the water vapor flux from six different locations of a small group of human participants. It is found that the WASP can not only measure and distinguish between insensible sweating (i.e., TEWL) and sensible sweating (i.e., thermal sweating) but also track skin dehydration-rehydration cycles. Comparisons with a commercial TEWL device, AquaFlux, show that the results obtained by both devices agree well. The WASP will be broadly applicable to clinical, cosmetic, and biomedical research.

A study of short period Indoor air pollution analysis in home level and its recommendations


 India had large number of villages (6.50 lakhs) around the cities and Tamil Nadu state having 12,619 villages around the town. Due to urbanization, village peoples having less number of job opportunities in their own village. The house holds women in villages use their country wood fuel for their long term cooking at low cost. The rural outside air having more air pollution as compared to indoor air pollution in the ratio of 2:1 in villages. The most significant parameters were identified and air quality levels at specific place were determined with help of PM2.5, PM10, Temperature and Humidity. The village women are affected more by skin allergy, asthma, eye power loss in advance, and cancer at various levels due to long usage of country wood. In general, village men using tobacco based items like cigarette and other items. This project deals with monitoring indoor air pollution in a village house (for a middle class income family) and better understanding of indoor air quality in real time. Also, it focuses on village women facing other health-related problems like asthma, eye problems and cancer in large numbers continuously increasing day by day in a village environment. It affects the normal work done by the villagers. A powerful statistical tool also used to compare the relationship between the indoor parameters in a selected village.

Energy saving potential analysis of a short cycling industrial air compressor in a marine equipment manufacturing plant in Türkiye

Compressed air systems are recognised as significant energy users and are characterised by their notably inefficient energy consumption. This ensures their significance and potential for decarbonisation through cleaner and more responsible energy consumption in manufacturing facilities, such as marine equipment manufacturing plants in the shipbuilding industry, in order to address the various economic and regulatory challenges related to energy use and climate change. In the relevant literature, there are numerous studies on various energy-saving measures for compressed air systems; however, none concentrates on the problem of short-cycling phenomena and associated energy-saving potential. In this study, using a novel and systematic energy audit methodology, a detailed energy audit of a rotary-type screw air compressor was conducted at a marine equipment manufacturing plant in Türkiye. The systematic energy audit methodology was based on the measurement of power consumption and the evaluation of various operation parameters to assess the existing performance of the compressor, including compressed air demand, compressed air production, cycle speed, air tank volume, specific capacity, and duty cycle. The audit results revealed that the air compressor was short cycling, resulting in excessive energy consumption. Comprehensive technical and economic assessments were conducted to determine the root cause of the compressor's short cycling and to identify energy-saving potentials. It was determined that the compressor was oversized relative to the plant's compressed air demand patterns, while the air tank was inadequately sized, causing the compressor to engage in short cycling. To replace the existing short-cycling compressor, a scenario analysis revealed that the deployment of an optimised system consisting of a fixed-speed baseload compressor and a variable-speed trim compressor can reduce the plant's energy consumption for the compressed air system by a significant 73%. This results in annual energy savings of 74,160 kWh, annual cost savings of €9.373,8, and an annual reduction of approximately 49,9 tonnes of carbon emissions. This application requires an initial investment of €24.280 and is anticipated to redeem itself in 2,2 years. Moreover, it is anticipated to generate a net present value of €147.602 over its 20-year lifespan.

Research on DC arc fault detection in PV systems based on adjacent multi-segment spectral similarity and adaptive threshold model

This paper proposes a practical adaptive detection method of series DC arc that could be more adaptable to PV systems’ intricate and complex environment than conventional detecting methods. Firstly, The discharge in a short air gap with unsymmetrical dielectric-covered electrodes will bring additional noise interferences to the current of the circuit where the arc is located and give rise to the alternation of the spectrum of the noise current. By analyzing the current noise spectrum before and after the occurrence of a DC arc fault, it was found that the adjacent multi-segment spectral similarity (AMSSS) characteristic could identify the event of the mark. Secondly, an algorithm architecture using principal component analysis(PCA) of AMSSS and integrated φ-statistic was used to determine an adaptive threshold model. Finally, to validate the fidelity and resilience of the pattern, a photovoltaic plant platform containing 20 PV modules and one three-phase inverter was constructed to acquire relevant data. Then, validation of the adaptive thresholding model was implemented by including several sets of tests generated under different conditions, such as normal, shading, inverter start-up, crosstalk, and arcing conditions. According to the comparative tests, We tentatively conclude that the adaptive model has a relatively strong arc detection capability and high environmental adaptability and could be applied to natural PV systems.

Characteristics and Species Composition of the Subalpine and Alpine Grasslands of Goygol National Park

By the order of the President of the Republic of Azerbaijan dated April 1, 2008, Goygol National Park was established in the administrative territories of Goygol, Dashkasan and Goranboy districts from 6739 hectares to 12755 hectares. The grassland vegetation of Goygol National Park and the lake ecosystem it surrounds is one of the floristically rich regions of the Caucasus. The richness and diversity of flora is related to the geomorphological complexity of the area. On the other hand, the reserve regime allows the protection of vegetation. Modern subalpine vegetation has changed dramatically as a result of mowing and grazing. Thus, short (13-15 cm) grass or grass-steppe plant groups have formed in the place of relatively tall plants that existed earlier in many pasture areas. The flora composition of subalpine meadows is much richer than the meadow associations of other mountain zones. 70-80 (100) flowering plants were recorded in many vegetation groups. The climate of the Alpine belt is distinguished by its harshness. Short summer (2.0-2.5 months), low air and soil temperature, abundance of atmospheric precipitation, etc. are characteristic features of the alpine zone.

Design and Research of the Image Processing Unit and Telemetric Equipment for the Laser-Guided Very Short Range Air Defence Systems Field Simulator

In this article, the engineering concept of the laser-guided very short range air defence system field simulator, its structure, and practical use are presented. The possibilities and advantages of the practical use of the equipment developed in tactical exercises and individual training of air defence specialists are shown. The field simulator equipment without invasion and compromising functionality into the combat air defence system has been connected and installed. The simulator performs all required shooting procedures without using combat missiles, target detection, shot execution, and maintaining the target in the sighting lens until its destruction. The field simulator reduces training process expenses and increases its efficiency. In the article, the ground control and onboard control units are presented. The units consist of target detection and its positioning, coordinate defining and data transmission (global positioning system (GPS), personal computer (PC), radio frequency (RF) transceiver), pyrotechnic charge for missile launch simulation, and target destruction devices (e.g., smoke generator), whose operating principles, functional capabilities, and work reliability are ensured on the basis of conducted research. The field simulator, which was created based on synthesising the simulator systems studied, has proven itself in practise.

Numerical Calculation of Direct Current Breakdown Voltage for Complex Short Air Gaps under Varying Altitudes

With the increasing construction of ultra-high voltage direct current transmission in high-altitude environments, it becomes crucial to explore the impact of altitude on the short-gap discharge characteristics. To this end, this study proposes a finite element simulation and calculation method for the direct current (DC) breakdown voltage of actual complex short-gap structure under varying altitudes based on the Townsend criterion and the streamer criterion. The method is verified by combining the discharge experiments in Beijing, Qinghai, and Tibet. The results demonstrate that this method can effectively calculate the DC breakdown voltage of gaps between damping capacitors with a relative error range of -3.64% to 0.2%. The research results provide new insights for insulation evaluation of short-gap structures under varying altitudes.

Persistence of auditory modulation of wind-induced escape behavior in crickets.

Animals, including insects, change their innate escape behavior triggered by a specific threat stimulus depending on the environmental context to survive adaptively the predators' attack. This indicates that additional inputs from sensory organs of different modalities indicating surrounding conditions could affect the neuronal circuit responsible for the escape behavior. Field crickets, Gryllus bimaculatus, exhibit an oriented running or jumping escape in response to short air puff detected by the abdominal mechanosensory organ called cerci. Crickets also receive a high-frequency acoustic stimulus by their tympanal organs on their frontal legs, which suggests approaching bats as a predator. We have reported that the crickets modulate their wind-elicited escape running in the moving direction when they are exposed to an acoustic stimulus preceded by the air puff. However, it remains unclear how long the effects of auditory inputs indicating surrounding contexts last after the sound is terminated. In this study, we applied a short pulse (200ms) of 15-kHz pure tone to the crickets in various intervals before the air-puff stimulus. The sound given 200 or 1000ms before the air puff biased the wind-elicited escape running backward, like the previous studies using the longer and overlapped sound. But the sounds that started 2000ms before and simultaneously with the air puff had little effect. In addition, the jumping probability was higher only when the delay of air puff to the sound was 1000ms. These results suggest that the cricket could retain the auditory memory for at least one second and alter the motion choice and direction of the wind-elicited escape behavior.

Polarization control of terahertz waves generated by a femtosecond three-color pulse scheme

Polarization characteristics of terahertz waves generated from a short air plasma excited by femtosecond three-color pulses with a frequency ratio of 1:2:3 have been theoretically investigated, and the results show that flexible and effective control of terahertz polarization can be achieved by means of changing the polarization combination and relative phase of three-color pulses, which is related to the electric field spatiotemporal distribution of the synthetic pulse formed via three-color pulse superposition. The complicated spatiotemporal distribution can be made clear by analyzing the projection component of the electric field in the three-dimensional Cartesian coordinate system. For terahertz waves generated from a short air plasma filament, the proposed method of terahertz polarization control on the basis of a three-color pulse scheme can be realized by ordinary multi-cycle laser pulses and overcome the disadvantage of few-cycle laser pulses utilized to obtain nearly circularly polarized intense terahertz waves or elliptically polarized intense terahertz waves with large ellipticity in the two-color pulse scheme.

Effects of rod radius and voltage on streamer discharge in a short air gap

Streamer discharge is the inaugural stage of gas discharge, and the average electron energy directly determines the electron collision reaction rate, which is a key parameter for studying streamer discharge. Therefore, taking into account the average electron energy, this work establishes a fluid chemical reaction model to simulate and study the course of evolution of a streamer discharge in a 5 mm rod–plate gap, considering 12 particles and 27 chemical reactions. It introduces the electron energy drift diffusion equation into the control equation, and analyzes the temporal and spatial changes of average electron energy, electric field intensity and electron density with change in rod radius and voltage. The effects of voltage and rod radius on the course of streamer discharge can be reflected more comprehensively by combining the average electron energies. Three different values of 0.3 mm, 0.4 mm and 0.5 mm are set for the rod radius, and three different values of 5 kV, 6 kV and 7 kV are set for the voltage. The influence of an excitation reaction on the streamer discharge is studied. The findings indicate that, as voltage raises, the streamer head’s electron density, electric field and average electron energy all rise, and the streamer develops more quickly. When the rod radius increases, the electron density, electric field and average electron energy of the streamer head all decrease, and the streamer’s evolution slows down. When an excitation reaction is added to the model, the average electron energy, the magnitude of the electric field and the density of electrons decrease, and the evolution of the streamer slows down. An increase in average electron energy will lead to an increase in electric field strength and electron density, and the development of the streamer will be faster.

TEKNIK SINEMATOGRAFI FILM PENDEK AIR MATA IMPIAN KARYA MULTIMEDIA DARUSSALAM BLOKAGUNG BANYUWANGI

The main objective of this article is to find out what cinematographic techniques are used in the short film entitled Air Mata Impian by Multimedia Darussalam in terms of cinematographic techniques. This study used a qualitative research method with a qualitative descriptive type. In this study, researchers describe or construct theories that exist in depth on research subjects. In this research, the object of research is to analyze the cinematographic techniques applied in the film Air Mata Impian by MMD. The results of the research in this article show that the cinematographic techniques analyzed include the camera angle formula 5C, close up/shot size, composition, continuity, and cutting. There are 5 cinematographic techniques of Joseph V. Mascelli A.S.C which were also carried out by the Multimedia Darussalam Team in making the short film Air Mata Impian, namely camera angle, close up/shot size, composition, continuity, and cutting/editing.

Weekly carbon dioxide exchange trend predictions in deciduous broadleaf forests from site-specific influencing variables

Weekly net-ecosystem-exchange (NEE) data recorded and verified over multiple years, together with site-specific influential ecological variables, for distinct deciduous-broadleaf-forest (DBF) sites in North America can reveal useful relationships regarding their functions as long-term carbon dioxide (CO2) sources and sinks. Machine learning (ML) and regression models have greater success at predicting weekly NEE from some DBF sites than others, from the available site variables. In particular, support vector regression (SVR) and extreme gradient boosting (XGG) ML methods perform better than multi-linear regression in the weekly NEE predictions they generate using up to 24 influential variables. The DBF sites studied are distinguished into those that have followed distinctive, albeit fluctuating seasonal NEE trends, and those that are characterized by abrupt fluctuations in NEE across the leaf-on season. ML models predict weekly NEE for the former sites more reliably than for the latter sites. Consideration of the relative influence of the variables on the XGB and regression model NEE predictions identifies which variables are most influential at specific sites. Short wave radiation (in and out) and air temperature are found to be variables exerting substantial influence on the prediction models for the sites studied. From the prediction results and the relative influences of the available environmental variables, it is concluded that complex processes are involved at those sites showing rapid NEE fluctuations in the leaf-on seasons that are not readily detectable from the environmental variables currently being continuously recorded at those sites.

Stator current identification in generator among single and composite faults composed by static air‐gap eccentricity and rotor inter‐turn short circuit

In this study, a fault diagnosis model based on magnetic density is proposed to analyse the current characteristics of synchronous generator rotor inter-turn short circuit and air gap eccentric single fault and composite fault. The model considers the influence of rotor inter-turn short circuit and air gap eccentricity on air gap magnetic density. According to two main factors, the short circuit turns and eccentric distance, are used to reflect the short circuit and eccentricity of the generator. The detailed parameter input model of the generator can easily and quickly predict the development trend of these current parameters based on the air gap magnetic density. And the phase current is selected as the current parameter. The validity of the proposed model is verified by two-dimensional finite element analysis and experimental research.