Wind Zone Research Articles

Frequency-Response Methods for Synthesizing Controlled High-Speed Electric Drives of Compressors

Frequency-response methods for analyzing and synthesizing current and electromagnetic torque control loops in alternating-current electric drives are proposed. It is shown that, when solving the problems of analysis and synthesis of the current and torque control loops, the unchanged part of the electric drive can be approximated by a linear system with the amplitude-modulated signal. It has been established that the transient and steady-state processes of variables in the motor’s phase windings can be considered in the current and torque loops independently. The use of frequency-response methods for identification of controlled objects allows consideration of the cross-magnetic links between the three-phase windings of the electric machine and the mathematical description of the system can be represented by a simplified set of equations, which is convenient for setting up and adjusting the system by engineering personnel. Using experimental Bode plots, it has been shown that the steady frequency passband in the current control loop can reach 4000 rad/s, which facilitates the adjustment of the toque control loop when the drive is running at a speed of 6000 rpm. A further increase in the speed of the drive with the specific mass and dimensional parameters preserved at the same level can be achieved only by introducing correction signals. It is shown that in multiphase electric drives with more than three phases, the phase winding zone decreases and the leakage inductive reactance of the phase winding decreases, which allows a significant expansion of the frequency passband in the current, torque, and speed control circuits.

Expressions of TGF-β1 and EⅢA-FN after Rat Skeletal Muscle Contusion and Wound Age Estimation.

Objective To study the expressions of transforming growth factor-β1 （TGF-β1） and EⅢA-fibronectin （EⅢA-FN） at different time points of antemortem injury, antemortem injury postmortem expression and postmortem injury and to explore their application value in wound age estimation. Methods A model of rat skeletal muscle contusion was established. The rats were randomly divided into normal control group （n=5）, antemortem contusion group （n=40）, antemortem contusion postmortem expression group （n=110） and postmortem injury group （n=25）. The expressions of TGF-β1 and EⅢA-FN after rat skeletal muscles antemortem contusion were detected with immunohistochemical staining. Expression changes of TGF-β1 and EⅢA-FN mRNA in each group were analyzed with real-time fluorescence quantitative PCR. Results Immunohistochemical staining results showed that a large number of polymorphonuclear leukocyte, mononuclear cells and fibroblastic cells showed a strong expression of TGF-β1 in wounded zones 12 h-14 d after antemortem contusion. EⅢA-FN was mainly distributed in the extracellular matrix, 3 to 7 d post-traumatic. Real-time fluorescence quantitative PCR results showed that TGF-β1 and EⅢA-FN mRNA in antemortem injury group reached the peak at 3 and 5 d post-traumatic respectively. The expressions of TGF-β1 and EⅢA-FN mRNA in antemortem contusion postmortem expression group peaked at 6 h and 12 h postmortem. The expression of TGF-β1 and EⅢA-FN mRNA in postmortem injury group 0.5-12 h postmortem was significantly lower than those of the normal control group and the antemortem contusion group. Conclusion TGF-β1 and EⅢA-FN might become a reference index for skeletal muscle wound age estimation.

Fragility analysis of the roof structure of low-rise buildings subjected to tornado vortices

The fragility curves of roof failures for wood-frame low-rise building were developed in this study with the focus on the roof sheathing panels and roof-to-wall connections. Two different nail spacings for roof sheathing panels and three types of roof-to-wall connections were considered. This study focused on the first failure of roof sheathing panels without considering the sequential loss of the sheathing panels, and the unit failure of effective wind zones containing different numbers of roof-to-wall connections. The tornado simulator-based dataset was used for determination of the statistics of wind loads, without considering the translational motion effects of tornado vortices. The results show that the failure probability of roof is dependent on the proximity of a tornado to a building and the opening azimuth on walls. Additionally, the combined effects of pressure drop and aerodynamic interactions dominate the failure modes of roof system. The obtained fragility curves in this study can be used to estimate the maximum tangential wind speed of the tornado vortices and the local oncoming tangential wind speed at roof height. The estimation of tornado intensity using the present results is likely to approach the lower-bound of wind speed estimation in WSEC (2006) report.

Comparisons suggest more efforts are required to parameterize wind flow around shrub vegetation elements for predicting aeolian flux

Upon interacting with the atmosphere, vegetation could alter the wind distribution and consequently the erodibility of nearby region. The parameterization of wind distribution around vegetation is crucial for the prediction of surface aeolian flux. This paper compared the performances of existing empirical distribution models in the estimation of aeolian flux for shrub vegetation, focusing on distribution pattern and vegetation porosity (main parameter of distribution function). Predicted dust fluxes directly entrained by air flow show weak sensitivity to both distribution pattern and porosity in the case of low vegetation density, which suggests some aspects in dust forecast models might be simplified. However, both distribution pattern and porosity show significant effect on sand saltation transport rate in the lee of vegetation element and, consequently, on the formation and evolution of surface aeolian landforms. The contribution of dust fluxes released in wind increase zone to the total emission by using current parameterizations increases with both the decrease of wind speed and the increase of vegetation density. Nevertheless, the parameterization of wind increase zone needs to be validated and improved by further experimental and numerical investigations.

Short-Term Spectral Variability of the Herbig Ae/Be Star HD37806

The spectroscopic variability of the Herbig Ae/Be star HD 37806 is analyzed on temporal scales from night-to-night, and over individual nights. The observations were made during November 2012 on the ASP-14 Coude spectrograph installed on the 2.6-m ZTSh telescope at the Crimean Astrophysical Observatory. 40 spectra in the region of the Ha and HeI 5876 lines were obtained over 4 nights. An analysis of the observed variability of the profiles of these lines shows that: (a) the variations in the Ha profiles are well explained under the assumption that they are vibrationally modulated by local azimuthal inhomogeneities in the wind zone and (b) the rapid variability of the HeI 5876 line in the form of standing intensity waves in the region of a red absorbing component is additional evidence of the presence of a magnetosphere in HD37806 that contains local accretion fluxes that rotate rigidly in the star’s magnetic field.

Wind Energy Potential Assessment and Mapping Through Various Distribution Techniques: an Experimental Investigation for Wind Zone

The conventional energy resources are limited and they are reducing gradually. Therefore, energy production through renewable sources has acquired the maximum attention across the globe. Concurrently, the power crises have escalated especially in the developing countries like Pakistan. It was reported that 1/3rd of the population in the country is still not connected with the power grid. This is an alarming issue that requires the immediate attention for the socio-economic growth of the country. Therefore, the energy policy advisors in Pakistan must consider renewable energy (RE) as a prime source of electricity generation due to its adequate and continual availability. In this study, the authors focused on wind energy and they proposed the Umerkot site located in the Sindh province to evaluate the wind energy potential based on various Weibull distribution techniques such as Empirical, Graphical, Maximum likelihood estimation, Energy pattern factor and modified maximum likelihood estimation method. The performance is tested based on the three statistical methods, such as root mean squared error (RMSE), the coefficient of correlation (R) and coefficient of determination (R2). Moreover, the capacity factor (CF) and energy produced (EP) from different wind turbine (WT) models are also estimated. From the analysis, it is noticed that the proposed site has a huge potential of wind for power generation and it can be utilized for utility purpose. Furthermore, if exploited, it will help in reducing energy shortage in the countryside which badly affected the economic growth.

Structural reliability of elevated water reservoirs under wind loading

In the field of civil engineering, concrete water storage tanks are considered as hydraulic structures occupying a special place among other structures. The location of these tanks is based on hydraulic considerations related to the desired service pressure for subscribers whose solution is obtained by a compromise with the topographical constraints. In southern Algeria and the highlands; in order to ensure adequate pressure in the drinking water supply networks, the tanks are then elevated to high heights, which puts them under significant stress during windstorms and sandstorms conditions that are frequent in the South Algerian. As the severe weather conditions due to high winds are common, the elevated water storage tanks are designed to withstand to winds speeds included between 25 and 31 m/s according to the Algerian Wind Code. Given the uncertain and randomness of this phenomenon, the classical deterministic calculations of the engineer become limited since they do not integrate the notion of failure probability of the structure. In this study, a probabilistic approach based on Monte Carlo simulations is used to analyze the reliability of elevated water tanks submitted to hazard storm of wind loading. The limit state functions are related to the ultimate and serviceability limit states of the concrete elevated tank under wind analysis. This reliability approach, takes into account mainly two parameters which are the wind speed and the concrete compressive strength considered as random variable. Fragility curves depending on wind zones are obtained, where they demonstrate the dominant failure modes that can cause the structural failure.

Bending Stiffness, Load-Bearing Capacity and Flexural Rigidity of Slender Hybrid Wood-Based Beams

Modern architecture suggests the use of opened spaces with large transparent envelope surfaces. Therefore, windows of long widths and large heights are needed. In order to withstand the wind loads, such wooden windows can be reinforced with stiffer materials, such as aluminium (Al), glass-fibre reinforced polymer (GFRP), and carbon-fibre reinforced polymer (CFRP). The bending stiffness, load-bearing capacity, and flexural rigidity of hybrid beams, reinforced with aluminium, were compared through experimental analysis, using a four-point bending tests method, with those of reference wooden beams. The largest increases in bending stiffness (29%–39%), load-bearing capacity (33%–45%), and flexural rigidity (43%–50%) were observed in the case of the hybrid beams, with the highest percentage of reinforcements (12.9%—six reinforcements in their tensile and six reinforcements in their compressive zone). The results of the experiments confirmed the high potential of using hybrid beams to produce large wooden windows, for different wind zones, worldwide.

Global Quantities Computation Using Mesh-Based Generated Reluctance Networks

Global Quantities Computation Using Mesh-Based Generated Reluctance Networks

High-resolution dataset of urban canopy parameters for Beijing and its application to the integrated WRF/Urban modelling system

The Weather Research and Forecasting (WRF) model with urban canopy model has been widely used to study atmospheric boundary layer processes and urbanization-related environmental issues. One of the most daunting challenges faced by the integrated WRF/urban modelling system is constraining the uncertainties in urban canopy parameters (UCPs) that represent the urban morphological characteristics. In this paper, we develop a dataset of three-dimensional (3-D) UCPs for Beijing by using vector-format building information in a Geographic Information System (GIS) environment and apply it to the integrated WRF/urban modelling system to investigate the effects of UCPs on the simulated meteorological variables against observations in clear-sky days. Moreover, the role of spatially-varying UCPs involved in the Building Effect Parameterization (BEP) in capturing the heterogeneous characteristics of 2-m surface air temperature and 10-m wind field in the urban areas are evaluated. In general, high-resolution dataset of UCPs improves the model skill in simulating the diurnal variations and spatial distributions of 2-m surface air temperature and 10-m wind speed in the urban canopy, especially for the BEP. WRF/BEP with gridded UCPs dataset shows a better performance in densely built-up areas, where the morphological and physical characteristics of urban surface are complex. It also performs better in capturing the characteristics of urban heat islands (UHIs) and weak wind zones (WWZs) in urban areas. Results show that introducing the 3-D UCPs dataset into the integrated WRF/urban modelling system is a simple and yet efficient way to enhance the modelling capabilities in urban areas and assist urban planners to deal with urban environmental issues.

Techno‐economic analysis of power generation from a potential wind corridor of pakistan: An overview

Since the consumption of non‐renewable sources is diminishing day‐by‐day, most of the developing countries across the globe are facing a severe energy crisis. This energy crisis affects the developing countries such as Pakistan so extensively that population has a crucial problem of load shedding for long hours. Thus, there exists a fundamental need for alternative and economical energy resources, for example, solar, wind, and biofuel energy. Meanwhile, out of all the financially viable ways of power generation, the wind energy is considered as the most economical way. However, in this article authors selected six potential wind zones which lie within 1100 km of coastal zones. In this study, only 1‐year wind speed raw data is considered and taken from appropriate wind zones at various heights with the support of Pakistan Metrological Department. Besides all, this project encourages the domestic as well as the foreign investor to invest in the wind energy projects at windy zones, which basically opens the business doors for the community of Pakistan for power generation, which leads to overcoming the energy crisis along the countryside. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 706–720, 2019

Validation of an Improved Statistical Theory for Sea Surface Whitecap Coverage Using Satellite Remote Sensing Data.

The whitecap coverage at the sea surface is affected by the ratio of kinetic energy to potential energy, θ, the wave spectrum width parameter, ρ, and other factors. This paper validates an improved statistical theory for surface whitecap coverage. Based on the theoretical analysis, we find that the whitecap coverage is more sensitive to ρ than to θ, and the improved statistical theory for surface whitecap coverage is suitable in regions of rough winds and waves. The satellite-derived whitecap coverage data in the westerly wind zone is used to validate the improved theory. The comparison between the results from theory and observations displays a better performance from the improved theory relative to the other methods tested.

Tall building influence on city wind pattern

The population growth in big urban centers generates the necessity for tall buildings. This phenomenon happens also in tourist regions where it is necessary to host many people. However, locations with high buildings interfere with the flow of the wind and can affect the comfort and safety of pedestrians at street level. Tall buildings barrier reduces the natural ventilation in regions far from the beach. This work presents the results concerning the effects created by tall buildings on Mucuripe beach, Fortaleza, Brazil. We performed numerical simulations to verify the wind interference with buildings in an area of [Formula: see text][Formula: see text]m2, using the OpenFOAM toolbox, to solve the Reynolds Averaged Navier–Stokes (RANS) equations with the [Formula: see text]–[Formula: see text] turbulence model. The results showed how the obstacles alter the airflow. From them, one can identify the regions with reduced safety and pedestrian comfort, and also the weak wind zone created by the downstream of the constructions for the different wind directions that are locally observed.

A Clinical Test to Measure Airborne Microbial Contamination on the Sterile Field During Total Joint Replacement: Method, Reference Values, and Pilot Study.

Background:Airborne microbe-carrying particles in the operating-room environment during total joint replacement are a risk factor for periprosthetic joint infection. The present study focuses on a simple environmental test, based on practices used in aseptic cleanrooms, to quantify the deposition of microbe-carrying particles onto the sterile field.Methods:Settle plates are exposed Petri dishes. A settle plate test system and sampling plan were developed from current practices used in aseptic manufacturing. A pilot study evaluated this system in an orthopaedic operating room during 22 total knee and hip arthroplasties. The microbial deposition total (MDT), expressed in colonies/m2, is proposed as an outcome variable to report airborne sterile-field contamination as measured with settle plates. Two reference MDT levels were developed: (1) an upper limit of 450, corresponding with the ultraclean air definition of 10 colonies/m3, and (2) a target level of 100, corresponding with 1 colony/m3. These levels also correspond with widely used limits in aseptic cleanrooms and controlled environments.Results:High MDT standard deviations were noted. Ninety-one percent (95% confidence interval, 71.0% to 98.7%) of wound zone MDT levels were within the upper limit. Twenty-seven percent (95% confidence interval, 12.9% to 48.4%) of wound zone levels were within the target level.Conclusions:Settle plates are a feasible technique to test environmental levels of microbe-carrying particles on sterile fields during total joint replacement for scientific and environmental quality studies.Clinical Relevance:This settle plate operating-room environmental test can be used in future research to validate the presence of actual ultraclean-air conditions during periprosthetic joint infection outcome studies. Surgeons also can use this test to measure intraoperative airborne microbe-carrying-particle sterile-field contamination and compare it with ultraclean-air reference levels for environmental quality-control programs.

Skin-permeable liposome improved stability and permeability of bFGF against skin of mice with deep second degree scald to promote hair follicle neogenesis through inhibition of scar formation.

Excessive deposition of extracellular matrix (ECM) usually resulted in scar formation during wound healing, which caused skin dysfunction, such as hair loss. Basic fibroblast growth factor (bFGF) was very helpful for promoting hair follicle neogenesis and regulating the remodeling of ECM during wound healing. Because of its poor stability in wound fluids and low permeability against the dense wound scar, the repairing quality of bFGF on wound was hindered largely in clinical practice. To overcome these drawbacks, herein, a novel liposome with silk fibroin hydrogel core (bFGF-SF-LIP) was firstly prepared to stabilize bFGF, followed by insertion of laurocapam, a permeation enhancer, into the liposomal membrane to construct a skin-permeable liposome (SP-bFGF-SF-LIP). The encapsulated efficiency of bFGF was reaching to nearly 90% when ratio of drug/lipids above 1:300, and it activity was not compromised by laurocapam. SP-bFGF-SF-LIP exhibited a hydrodynamic diameter of 103.3 nm and Zeta potential of -2.31 mV. The stability of the encapsulated bFGF in wound fluid was obviously enhanced. After 24 h of incubation with wound fluid containing MMP-9, the remaining bFGF was as high as 65.4 ± 0.5% for SP-bFGF-SF-LIP, while only 2.1 ± 0.2% of free bFGF was remained. The skin-permeability of bFGF was significantly enhanced by SP-bFGF-SF-LIP and most of the encapsulated bFGF penetrated into the dermis. After treatment with SP-bFGF-SF-LIP, the morphology of hair follicle at wound zone was obviously improved and the hair regrew on the deep second scald mice model. The therapeutic mechanism was highly associated with inhibiting scar formation and promoting vascular growth in dermis. Conclusively, SP-bFGF-SF-LIP may a potential option to improve wound healing with high-quality.

The climatology of shamals in the Arabian Sea—Part 1: Surface winds

This study describes the climatology of shamal winds in the Arabian Sea using recent 30 years (1987–2016) of ERA‐Interim winds. The shamal events were distinguished based on the typical directions, duration and intensity of the winds. Three potential zones of shamal winds were identified in the northwestern Arabian Sea, which are the areas where the predominant shamal swells have been generated. The number of events, duration and intensity of shamal winds were estimated for various months and years. The climatology and trends of shamal winds were derived and the spatial extent of the winds was assessed. The results show that the number of events and the duration of shamals decrease in the northwestern Arabian Sea. Contrasting trends have been observed in the shamal intensities—significant positive trends in the Gulf of Oman and significant negative trends along the east coast of Oman. The trends of the total winds are in contrast with those of the shamals winds.

The many faces of pulsars – the case of PSR B0833-45

A review of observational properties of the Vela pulsar across a wide energy spectrum is given. Then current approaches to the modelling of pulsars and their wind zones are briefly presented. The challenges posed to the models by the diversity of Vela’s light curves in different energy ranges are discussed.

Lateral strength and deflection of cold-formed steel shear walls using corrugated sheathing

Recent research has proven that cold-formed steel shear wall with corrugated steel sheathing is a promising lateral force resisting system in high wind and seismic zones. Extensive experimental investigations, including monotonic and cyclic tests on cold-formed steel shear walls with corrugated steel sheathing, were recently completed at University of North Texas. This paper summarizes previous and newly conducted tests and presents finite element analyses in order to establish a set of nominal shear strengths for the corrugated steel sheathed shear walls. In addition, a design method for determining the deflection of the corrugated steel sheathed shear walls under in-plane lateral loading was proposed based on the experimental results and nonlinear regression analyses. The deflections obtained from the proposed design equation were compared with the test deflections and good agreement was obtained.

Effects of exogenous high mobility group protein box 1 on angiogenesis in ischemic zone of early scald wounds of rats

Objective: To observe effects of exogenous high mobility group protein box 1 (HMGB1) on angiogenesis in ischemic zone of early scald wounds of rats. Methods: Thirty-six Sprague-Dawley rats were divided into HMGB1 group and simple scald (SS) group according to the random number table, with 18 rats in each group. Comb-like copper mould was placed on the back of rats for 20 s after being immersed in 100 ℃ hot water for 3 to 5 min to make three ischemic zones of wound. Immediately after scald, rats in HMGB1 group were subcutaneously injected with 0.4 μg HMGB1 and 0.1 mL phosphate buffer solution (PBS), and rats in SS group were subcutaneously injected with 0.1 mL PBS from boarders of ischemic zone of scald wound. At post scald hour (PSH) 24, 48, and 72, 6 rats in each group were collected. Protein expressions of vascular endothelial growth factor (VEGF) in ischemic zone of wound at PSH 24, 48, and 72 and protein expressions of CD31 in ischemic zone of wound at PSH 48 and 72 were detected by immunohistochemistry. The number of microvessel in CD31 immunohistochemical sections of ischemic zone of wound at PSH 48 and 72 was calculated after observing by the microscope. The mRNA expressions of VEGF and CD31 in ischemic zone of wound were detected by real-time fluorescence quantitative reverse transcription polymerase chain reaction at PSH 24, 48, and 72. Data were processed with analysis of variance of factorial design, t test, and Bonferroni correction. Results: (1) At PSH 24, 48, and 72, protein expressions of VEGF in ischemic zone of wound of rats in HMGB1 group were significantly higher than those of rats in SS group (t=7.496, 4.437, 5.402, P<0.05 or P<0.01). At PSH 48 and 72, protein expressions of CD31 in ischemic zone of wound of rats in HMGB1 group were 0.038 8±0.007 9 and 0.057 7±0.001 2 respectively, significantly higher than 0.013 4±0.004 9 and 0.030 3±0.004 0 of rats in SS group (t=10.257, 15.055, P<0.01). (2) At PSH 48 and 72, the number of microvessel in ischemic zone of wound of rats in HMGB1 group was obviously more than that of rats in SS group (t=3.536, 4.000, P<0.05). (3) At PSH 24, 48, and 72, mRNA expressions of VEGF in ischemic zone of wound of rats in HMGB1 group were significantly higher than those of rats in SS group (t=4.406, 3.821, 3.356, P<0.05). At PSH 24 and 48, mRNA expressions of CD31 in ischemic zone of wound of rats in HMGB1 group were significantly higher than those of rats in SS group (t=4.113, 3.466, P<0.05). At PSH 72, mRNA expressions of CD31 in ischemic zone of wound of rats in 2 groups were close (t=0.010, P>0.05). Conclusions: Exogenous HMGB1 can promote angiogenesis in ischemic zone of early scald wounds of rats by increasing expressions of VEGF and CD31.

Spectral Variability of the Herbig Ae/Be Star HD 37806

Results are reported from a spectroscopic study of the Herbig Ae/Be star HD 37806 from 2009 through 2017 using high resolution spectrographs at the Crimean Astrophysical Observatory and the OAN SPM Observatory in Mexico. 72 spectra of this object near the Hα, Hβ, HeI 5876 and D NaI lines are analyzed. The following results were obtained: 1. The type of spectral profile of the Hα line can change from P Cyg III to double emission and vice versa over a time scale on the order of a month. 2. Narrow absorption components are observed in the profiles of the Hα and D NaI lines with radial velocities that vary over a characteristic time on the order of a day. 3. On some days, the profiles of the Hβ, HeI 5876, and D NaI lines show signs of accretion of matter to the star with a characteristic lifetime of a few days. A possible interpretation of these phenomena was considered. The transformation of the Hα profile may be related to a change in the outer latitudinal width of the boundary of the wind zone. The narrow variable absorption lines may be caused by the rotation of local azimuthal inhomogeneities in the wind zone owing to the interaction of the disk with the star’s magnetosphere in a propeller regime. Several current theoretical papers that predict the formation of similar inhomogeneous wind structures were examined. It is suggested that the episodes with signs of accretion in the spectral line profiles cannot be a consequence of the modulation of these profiles by the star’s rotation but are more likely caused by sudden, brief changes in the accretion rate. These spectral observations of HD 37806 should be continued in a search for cyclical variability in the spectral parameters in order to identify direct signs of magnetospheric accretion and detect possible binary behavior in this object.