Disturbed Conditions Research Articles

IMPORTANCE OF PSEUDOMONAS SYRINGAE AS BIOLOGICAL AEROSOL IN CLOUDS AND ITS ENVIRONMENTAL EFFECT

Earth temperature ascend because of modern disturbance caused by petroleum products which produce heat entangling gases and cause an unnatural weather change. Rising temperature is disturbing condition for whole globe. Rainfall is the principal source for water and soil moisture within the semi-arid and dry places in the world. Due to temperature shift less rainfall affect agriculture turns into vulnerable and plants faces severe water shortages. So drought is a prime concern in many countries like UAE. Many countries using cloud seeding is a ultimate solution for drought. All around the world generally salts are utilized as cloud seeder. Silver iodide, dry ice, and potassium iodide are the most widely recognized as cloud nuclei. These chemical aerosols in cloud seeding might possibly harm the climate, particularly the plants as well as also adversely effect on human health. Biological ice nuclei are different from these chemicals for the reason that bacteria are more effective ice nuclei than salt particles, because of their sizes and there working temperatures. This study’s goal is to concentrate on the impact of biological aerosol on cloud seeding and the environment. The findings of this study demonstrate that certain P.syringae strains are more suited to survive in conditions that arise at high altitudes and in clouds. P.syringea have own advantages and drawbacks. Bacterial ice nuclei activity cause frost in plants and damage them. Using of pesticides to control the damage of plants by P.syringea adversely affect the climate. Involving genetic adjustment in P.syringea host plants the plants effectively guarded off the bacterial disease with practically no harm to the actual plants or the general climate.

Research on Model Predictive Control of a 130 t/h Biomass Circulating Fluidized Bed Boiler Combustion System Based on Subspace Identification

The structure of large biomass circulating fluidized bed (BCFB) boilers is complex, and control schemes for coal-fired boilers cannot be simply applied to biomass boilers. Multivariable coupling and operational disturbances are also common issues. In this study, a state space model of a 130 t/h BCFB boiler was established under different operating conditions. Using the 100% operating point as an example, a model predictive controller was designed and tested under output disturbance and input disturbance conditions. The results show that the predictive control system designed in this study has a fast response speed and good stability.

Simulation and Experiment of Active Vibration Control Based on Flexible Piezoelectric MFC Composed of PZT and PI Layer.

In order to improve the vibration suppression effect of the flexible beam system, active control based on soft piezoelectric macro-fiber composites (MFCs) consisting of polyimide (PI) sheet and lead zirconate titanate (PZT) is used to reduce the vibration. The vibration control system is composed of a flexible beam, a sensing piezoelectric MFC plate, and an actuated piezoelectric MFC plate. The dynamic coupling model of the flexible beam system is established according to the theory of structural mechanics and the piezoelectric stress equation. A linear quadratic optimal controller (LQR) is designed based on the optimal control theory. An optimization method, designed based on a differential evolution algorithm, is utilized for the selection of weighted matrix Q. Additionally, according to theoretical research, an experimental platform is built, and vibration active control experiments are carried out on piezoelectric flexible beams under conditions of instantaneous disturbance and continuous disturbance. The results show that the vibration of flexible beams is effectively suppressed under different disturbances. The amplitudes of the piezoelectric flexible beams are reduced by 94.4% and 65.4% under the conditions of instantaneous and continuous disturbances with LQR control.

Study on the Instability Mechanism of Coal and Rock Mining under a Residual Coal Pillar in Gently Inclined Short-Distance Coal Seam with the Discrete Element

The collapse of overlying rocks caused by the instability of residual coal pillars during lower coal seam mining significantly impacts its safety. This paper focuses on the gentle dipping coal seam group and utilizes the discrete element method (DEM) as the basis to comprehensively consider multiple factors through orthogonal experiments. In so doing it reveals the influence mechanisms of various factors on mining at a close distance under a residual coal pillar. Firstly, the process of lower coal seam mining under residual coal pillars in gently-dipping coal seams was simulated and analyzed based on a case study at the Baoping coal mine. Comparing the evolution characteristics of coal–rock fractures, stress changes, and displacement changes during the mining process reveals the mechanism of the joint instability of the lower coal seam, interlayer rock, coal pillars, and overlying strata under the disturbed conditions of lower panel mining. Secondly, an orthogonal simulation experiment was established using the width of the coal pillar and the thickness of the lower coal seam as variables. By comparing the development process of cracks, stress distribution, and rock displacement under different conditions, the research results indicate that the width of coal pillars has an impact on the maximum amount of coal pillar subsidence, while the thickness of the underlying coal seam has an impact on the time of subsidence, when hd ≥ 4.2 m (hj/hd ≤ 4) and w ≤ 14 m (w/hm ≤ 2), a large-scale collapse of the overlying strata of the coal pillar occurs.

LVRT and Reactive Power/Voltage Support of Utility-Scale PV Power Plants during Disturbance Conditions

This paper proposes a control technique for a large-scale grid-connected photovoltaic (PV) plant that maintains the connection of an inverter to the grid voltage under different types of faults, while injecting a reactive power to accommodate the required grid connection. This control strategy is suggested to improve the low-voltage ride-through (LVRT) capability of grid-connected PV power generation plants. A 20 MW solar PV power plant is modeled and simulated using Matlab/Simulink. The power plant is composed of 10 parallel groups of arrays with a power rating of 2 MWp. The solar PV arrays are connected to a medium-voltage side-rated 22 KV to the utility grid. A dynamic analysis of the grid-connected large-scale solar PV power plant is introduced. This analysis is accomplished in order to determine the impact of three-phase short-circuits at the point of common-coupling (PCC), where the solar PV power station is connected to ensure a practical voltage level by injecting active and reactive power. The reactive power support allows for faster restoration of voltage values at the PCC. When subjected to transient disturbances, the stability of the studied system relies on both the type of the disturbance and the initial operating situation. The disturbance may be either small, resulting from electrical load changes, or large, such as from a transmission line short-circuit (fault) and significant generator loss.

Analysis of Ionosphere Day to Day Variability using Parametric Methods on GPS TEC

The development of global positioning systems (GPS) has cleared the way for a better understanding of the globe and the systems surrounding the earth. The GPS signals that are sent out and received by GPS receivers are affected by severe space weather (in the ionosphere) as well as atmospheric weather and lithospheric disturbances. These disturbances not only result in inaccuracies in GPS location but also make it difficult to make the necessary corrections to those faults. The study of these perturbations is helpful in gaining an understanding of the phenomenal changes that occur in the ionosphere as a result of the Sun and its solar effects, which include solar flares, sunspot numbers, solar winds, geomagnetic fields, and natural disasters such as earthquakes and thunderstorms, among other things. In this study, an effort is made to highlight the distinctions between geomagnetic calm days and disturbed days that occurred in January 2022. The research is carried out by using parametric approaches to the GPS vertical total electron content (VTEC) at Hyderabad (17.4°N, 78.5°E), which is a station with a low height. An examination of the power spectral densities (PSDs) of both the tranquil and the disturbed conditions is carried out. The improvement in VTEC data was noted on two days in January 2022 that had low geomagnetic activity; these days were the 6th and 13th. On the sixth of January 2022, enhancements can be seen at the normalised frequencies of 0.4966 and 0.7683, with a power spectral density (PSD) of -10.14dB and -12.94dB, respectively. On the thirteenth of January 2022, enhancements can be seen at the normalised frequencies of 0.5005 and 0.956, with PSDs of -9.264dB and -8.392dB. When compared to the preceding records, it can be seen very clearly that the PSDs of both geomagnetically tranquil and disturbed days are rather comparable to one another.

Extracting Exospheric Temperature From Daytime Ionospheric Electron Density Profiles

AbstractGiven that the ionosphere is strongly determined by the thermosphere and its state depends on thermospheric parameters, we propose a new method to extract exospheric temperature (Tex) from electron density (Ne) profiles based on the relationship between the variations in Tex and Ne profiles established through simulation. Ne profiles and corresponding Tex from the Millstone Hill incoherent scatter radar (ISR) observations are used to test the method. ISR Ne profiles are used for Tex retrieval and ISR Tex is used to make a comparison with Tex calculated by model and retrieved Tex. The results show that the retrieved Tex effectively captures diurnal, anomalous and short‐period variations. The relative deviation between the retrieved–observed Tex is approximately 2%, which is significantly improved compared with the Mass Spectrometer Incoherent Scatter model, especially under disturbed conditions. This result confirms that thermospheric temperature variation can be deduced from ionospheric profiles and our method can be considered a useful tool to obtain Tex from Ne profiles.

Dynamic simulation study of the secondary frequency regulation of a 1000 MW thermal power unit assisted by flywheel energy storage

The rapid development of new energy sources has brought a certain impact on the original power grid structure, accelerated the wear of unit equipment, and affected the stability, safety, and economy of thermal power unit operation, so it is proposed to add an energy storage system to solve the above problems. To analyze the secondary frequency regulation effect of thermal power units assisted by a flywheel energy storage system, a mathematical model of the control strategy on both sides of the boiler, steam turbine, and flywheel permanent magnet synchronous motor is proposed, and a two-regional power grid model is built through MATLAB/Simulink to simulate the frequency regulation effect of units with or without energy storage participation through step disturbance and continuous disturbance, which are 0.045 and 0.023 p.u. MW. Under step disturbance, the frequency fluctuation of the coupled energy storage system changed by 0.025 228 p.u. Hz, the time for the system to return to a steady state was shortened by 5.85 s, the maximum change of the frequency of the system in Region 2 was reduced by 0.025 579 p.u. Hz, and under continuous disturbance, the fluctuation of the output power of the steam turbine in Region 1 was reduced by 0.022 982 p.u. MW. In summary, under the same disturbance conditions in the outside world, the use of flywheel energy storage to assist the frequency regulation of thermal power units can effectively reduce the frequency fluctuation of the system, reduce the fluctuation of the output power of the steam turbine, reduce the loss of mechanical equipment, and extend the service life of the unit to a certain extent.

Bioassessment of environmental quality based on taxonomic and functional traits of marine nematodes in the Bohai Sea, China

Free-living marine nematodes are valuable biological indicators for different environmental disturbances. Their taxonomic composition and functional traits often respond to environmental changes. In this study, marine nematodes, collected from the Bohai sea on the northeastern coast of China in 2014, were investigated in terms of their taxonomic composition and functional traits. Furthermore, the environmental quality of the investigated area was assessed based on nematode metrics. The studied nematode community showed spatial variation in taxonomic and functional composition, in response to changes in environmental variables such as sediment chlorophyll-a, phaeophytin-a, organic matter content, silt-clay content etc. Overall, high percentage of tolerant marine nematodes species or colonizers predominated, suggesting a disturbed environmental condition of the study area. Further results from the environmental quality assessment based on nematode metrics indicated a moderate quality status at the most investigated stations.

Activity budgets, responses to disturbance and novel behaviours in captive mountain chicken frogs Leptodactylus fallax

Mountain chicken frogs Leptodactylus fallax are assessed as Critically Endangered on the IUCN Red List due to threats including chytridiomycosis and habitat loss. Ex-situ populations underpin species survival, but captive management is hampered by incomplete species knowledge, including its behavioural biology. In sixteen adult frogs, we investigated enclosure usage, nocturnal activity budgets, and behavioural responses to varying levels of husbandry-related disturbance through instantaneous scan sampling of camera trap footage over forty-two consecutive nights. Enclosure usage was quantified through the application of modified Spread of Participation Indices (mSPI). We present the first detailed activity budgets published for this species and found that broad activity patterns of captive animals corresponded well with their wild conspecifics; taking refuge during the day and emerging at dusk into exposed areas of the enclosure. Some behaviours, especially hunting and bathing, were partially phased throughout the nocturnal period. Enclosure use was not even, with disproportionately large amounts of time spent using nest boxes and deep leaf litter, even at night, and the converse in thin leaf litter and elevated perches. Principal Components Analysis (PCA) identified a bold-shy behavioural grouping (movement and resting opposed to refuge behaviours) that was consistent across husbandry-related disturbance conditions. Randomisation analyses showed that disturbance significantly affected multiple measured behaviour, especially feeding, social interactions and vocalisation; the impact was associated with the degree of disturbance. Novel behaviours were also documented, which are thought to be related to courtship. Our data provide insights into the behaviour of mountain chicken frogs and highlight potential trade-offs between enclosure maintenance, veterinary intervention, and animal welfare. Keywords: Amphibians, behaviour, mSPI, disturbance, welfare, Zoo

Analysis Method of Primary Frequency Modulation Capability of Power System Based on GRNN

One of the most important key parameters in power network operation is power frequency. The power network will be affected by various disturbances in operation, and the frequency of the power network will show different fluctuations under different disturbances. Once the frequency of the power network deviates from the normal operation level, the power quality of the power network will decrease, and the power equipment will be in an abnormal operation state. With the development of power network, the scale of distributed microgrid with high uncertainty such as new energy is expanding increasingly, the proportion of UHVDC transmission lines is increasing, and the structure of power network is changing, which makes the regulation of power network frequency facing greater challenges. In this paper, relying on the mechanism of integrated load of power network and the participation of generator set in primary frequency modulation, the primary frequency modulation capability of 60 s power network under different frequency disturbance conditions is analysed, and the training and simulation prediction of GRNN generalized regression neural network prediction model are completed by using MATLAB software. By predicting of the generator set under different disturbances, the parameters related to the primary frequency modulation capability of the power network, such as the maximum amplitude of the active power fluctuation, the time when the maximum amplitude occurs and the time when the power network is restored to stability, are obtained to provide more accurate dispatching support for the dispatching side.

Robust Aircraft Flight Control in Conditions of Disturbances

. The landing phase during the flight is probably the most dangerous part, since most accidents occur at this stage. To reduce the influence of low-altitude wind shear on the longitudinal movement of the aircraft in the glide path landing mode (task), robust H – control is proposed. Dynamic models of the aircraft and wind shear are constructed. H2 and H∞ synthesis methods are investigated for the problem of controlling the flight of an aircraft in a vertical plane during landing under conditions of indeterminate disturbances. Both controls allow you to significantly reduce the height deviation. However, H∞ – suboptimal control provides better quality of transients both in height and speed than H2 optimal control. The simulation results of the synthesized system confirm the effectiveness of H∞ – control to increase robust resistance to uncertainties caused by wind disturbances

INVERSE NEURO-FUZZY MODEL BASED CONTROLLER DESIGN FOR A PH NEUTRALIZATION PROCESS

Since pH neutralization processes have extremely nonlinear characteristics, controlling it might be difficult. Therefore, a special controller design is needed to handle the high nonlinearities of the process. In this study, an inverse neuro-fuzzy model-based controller (NFMBC) design is presented for control of a pH neutralization process (NP). Input-output (IO) data set of the process is collected by applying a proper excitation signal. Then, forward and inverse neuro-fuzzy models of the process are constructed by using this data set after a training process. In terms of design simplicity, a two-input-one-output model structure is chosen for both neuro-fuzzy models. These forward and inverse neuro-fuzzy models are used in a nonlinear internal model control (NIMC) structure in order to provide robustness against disturbances and model mismatches. To examine the proposed controller's performance, simulation studies are carried out under setpoint variation and disturbance conditions. Additionally, the performance of the inverse NFMBC is compared to that of a fuzzy proportional integral derivative (FPID) controller with a 7x7 rule base. The results demonstrate that the designed controller provides more effective control performance for setpoint variations and also exhibits higher robustness against disturbances in the acid flow rate than the FPID controller.

A novel electric differential and synchronization control method for 4WD/4WS electric vehicles based on fictitious master

Electric Vehicles (EVs) have been typically proposed to replace conventional vehicles in the near future. The use of an Electric Differential (ED) in EV has many advantages like as high efficiency, low loosing, and lightweight mechanical differentials and transmissions with electric motors directly coupled to the wheels. In this paper, a novel ED mechanism for the four–Wheel–Drive (4WD)/two–Wheel–Steering (2WS) and 4WD/four–Wheel–Steering (4WS) EVs is proposed. The proposed ED is easy-to-implement and solves the problems of previous EDs. The speed synchronization action of all wheels is achieved by using the Fictitious Master technique. Moreover, for independent control of speed and torque, the Ackerman laws are applied to the motors. Also, the currents of EV are controlled with an indirect current vector controller. For a complete assessment of the proposed control method, the EV is analyzed under two different disturbances as positive and negative torque variations. The results showed that ED ensures both reliability and good path tracking. In addition, the robustness and stability of EVs under various disturbances are validated by producing new speed references for all wheels. The considered EV could robust under disturbance conditions, at an acceptable level. Moreover, the overlaps of torque and speed in the 4WD/4WS are about 15% and 23% more than 4WD/2WS, respectively. In essence, the proposed control method shows good results for EVs with various conditions: straight movement, turning, acceleration, and deceleration.

Effects of Hydrologic Regime Changes on a Taxonomic and Functional Trait Structure of Earthworm Communities in Mountain Wetlands.

Disturbances, both natural and anthropogenic, influence the patterning of species and species traits. The shift in species composition and distribution pattern of functional traits can demonstrate if the community is resistant, sensitive or resilient to the disturbance. Based on species- and trait-based approaches, we examined the response of the earthworm community to changing hydrologic conditions caused by the artificial drainage of mountain fens, in which cumulative effects of disturbance events over space and time are much less dynamic than in riverine wetlands. We hypothesized that the drainage-related changes of mountain fen peat soils have an effect on the earthworm community composition and its functional structure. We assume that the shift in species composition and value of community-weighted functional traits reflect changes in the resilience or resistance of the earthworm community to environmental change. Our results demonstrate that the total density of earthworms was almost three times lower under drained conditions compared to natural ones. Artificial drainage of fens had a neutral effect on the species-based diversity indices. However, there were species-specific traits that responded to hydrologic changes and which led to the species' replacements and to the co-occurrence of eurytopic, surface-browsing and more drought- and low-pH-resistant earthworm species in the drained fens. Based on these results, we conclude that abiotic-based environmental filtering was the main process responsible for sorting earthworms according to species and traits in the disturbed hydrologic conditions. The greater earthworm functional trait variations in semi-natural hydrologic conditions emphasizes the impact of transient dynamics in an altered disturbance regime on the earthworm assembly. Results also showed that in the changing hydrologic conditions of mountain fens, the functional trait approach revealed only slightly more predictive power than the taxonomic one, but it proved better with processes responsible for earthworm species filtering.

An implementation of an enhanced DG primary control equipped with fault detection scheme

ABSTRACT This paper proposes an enhanced primary control unit of the distributed generator inside the microgrid when the DG is grid-connected and when operated autonomously. The control methods needed for the DG inverter when operated in grid-connected mode and autonomous operation mode have been investigated. The rotating reference frame employed for the control of the DG has been clarified to investigate how the active and reactive power of the DG are delivered to the main grid. When the DG suffers from local disturbance conditions, it should be disconnected from the main grid and switched off or its control unit is changed to voltage-frequency mode. Therefore, a fault detection scheme has been implemented to monitor the voltage and frequency of the DG bus. Hence, the performance of the proposed work has been validated under steady-state and short circuit conditions where the DG inverter is operated in grid-connected mode, switch-off mode, and autonomous mode.

Bacterial Foraging Algorithm for a Neural Network Learning Improvement in an Automatic Generation Controller

The frequency diversion in hybrid power systems is a major challenge due to the unpredictable power generation of renewable energies. An automatic generation controller (AGC) system is utilised in a hybrid power system to correct the frequency when the power generation of renewable energies and consumers’ load demand are changing rapidly. While a neural network (NN) model based on a back-propagation (BP) training algorithm is commonly used to design AGCs, it requires a complicated training methodology and a longer processing time. In this paper, a bacterial foraging algorithm (BF) was employed to enhance the learning of the NN model for AGCs based on adequately identifying the initial weights of the model. Hence, the training error of the NN model was addressed quickly when it was compared with the traditional NN model, resulting in an accurate signal prediction. To assess the proposed AGC, a power system with a photovoltaic (PV) generation test model was designed using MATLAB/Simulink. The outcomes of this research demonstrate that the AGC of the BF-NN-based model was effective in correcting the frequency of the hybrid power system and minimising its overshoot under various conditions. The BP-NN was compared to a PID, showing that the former achieved the lowest standard transit time of 5.20 s under the mismatching power conditions of load disturbance and PV power generation fluctuation.

Fault-tolerant control for an electro-hydraulic servo system with sensor fault compensation and disturbance rejection

The electro-hydraulic servo system (EHSS) usually faces multiple sensor faults and disturbances, which is difficult to achieve good tracking control, reliability, and stability control. In this article, an advanced fault-tolerant controller is proposed for an EHSS to deal with the above challenge. The three fault observers, called nonlinear unknown input observers (NUIOs), are developed to effectively estimate the position, velocity, pressure sensor faults and the system states. The fault detection, estimation, and isolation are then presented as effective for multiple sensors failure at a time. The first NUIO for position sensor fault is utilized for the tracking control, while the other NUIOs are used for alarm proposal. The adverse effects caused by the matched and unmatched disturbances are eliminated by two extended state observers (ESOs). In addition, to avoid the “explosion of complexity” when computing the derivatives of virtual control laws, the dynamic surface control is applied to design the fault-tolerant control (FTC) scheme. The Lyapunov principle ensures system stability under lumped disturbance and faulty conditions. Finally, simulation studies and evaluation results are performed to demonstrate the validity of the proposed FTC algorithm.

Impact of Biotic Stress on Physiochemical Properties of Soil at Doodhpathri Kashmir

Anthropogenically disturbed soils have unique properties. In most of the ecosystems, especially under disturbed soil conditions, the soil properties are controlled by the accumulated materials. However, the equilibrium between the already present soil mass and the accumulated soil mass is very fragile and is affected by many factors. This study was carried out in the forest soil of Doodhpathri which is a famous tourist place in Kashmir in the spring and summer seasons at three sites (forest, meadow, and deforested sites) in 2019. Soil samples were collected at 15-30 cm depth. We determined soil texture, pH, electrical conductivity (EC), moisture, organic carbon (OC), available macronutrients (Nitrogen, Potassium, Phosphorus, Calcium, and Magnesium), and heavy metals (Copper; Cu, Nickel; Ni, Cadmium; Cd, Manganese; Mn, Lead; Pb, and Zinc; Zn). Soil texture analysis revealed the soils at all the study sites with a major proportion being comprised by the silt fraction and having a silty clay loam character. pH and electrical conductivity were found to be high at the deforested site in the summer. Organic carbon and moisture content were found higher at the forest site in summer and spring respectively. Nitrogen, potassium, and total bacterial count follow the same trend as higher concentration was found at the forest site in the summer while Phosphorus, magnesium, and calcium follow the same trend as their high concentration was found at the meadow site in the summer. Significantly higher values of heavy metals (Cu, Ni, Cd, Mn, Pb, and Zn) were found at the meadow site in the summer. The results could help to formulate conservation strategies for the soil at Doodhpathri that is affected by anthropogenic activities.

Refeeding Syndrome Awareness among Physicians of King Abdullah Medical City in Makkah, Saudi Arabia.

Refeeding syndrome (RFS) is a lethal condition of metabolic disturbances that arise from the sudden switch of metabolism from a state of starvation to one of nourishment. Quick recognition would reduce health complications. Physicians who are unaware of the syndrome will not identify and treat it. As nutritional risk is associated with the risk of RFS, physicians should be aware of it. To determine whether the physicians of King Abdullah Medical City (KAMC) in Makkah know of RFS and, if so, have skills in diagnosis and managing the syndrome. One hundred and fifty-nine physicians of KAMC were recruited in a cross-sectional study. They were asked to complete a questionnaire by face-to-face interview. The questionnaire was designed to capture physicians' knowledge and ability to manage RFS based on the awarding of certain scoring points. The level of knowledge among physicians had a significant association between knowledge and age (p = 0.021) and medical specialty (p = 0.010). Additionally, the most knowledgeable physicians were those who work in critical care (21.4%). Around 18% of physicians were not able to manage RFS. Lacking knowledge of RFS and how to manage it leads to critical life-threatening complications. Physicians need nutritional education to help them diagnose RFS and consult dietitians to avoid its complications.