Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 374 journals)
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 Arabian Journal for Science and EngineeringJournal Prestige (SJR): 0.303 Citation Impact (citeScore): 1Number of Followers: 1      Hybrid journal (It can contain Open Access articles) ISSN (Print) 2193-567X - ISSN (Online) 2191-4281 Published by Springer-Verlag  [2467 journals]
• MPPT Performance and Power Quality Improvement by Using Fractional-Order
Adaptive Backstepping Control of a DFIG-Based Wind Turbine with
Disturbance and Uncertain Parameters

Abstract: Abstract This paper proposes a fractional-order adaptive backstepping control (FOABC) with disturbance and uncertainty terms compensation for improving the MPPT (maximum power point tracking) performance and output power quality of a doubly fed induction generator (DFIG)-based wind turbine. In the proposed high-efficacy controller, disturbance and uncertainty terms are estimated in real time using an adaptive estimator designed using a recursion design process based on the nonlinear backstepping control. Meanwhile, a robust compensator is schemed and incorporated into the backstepping control algorithm so that it suppresses the effects of external disturbances and system uncertainties and, as a result, ensures the maximum wind energy extraction as much as possible, which is usually well known as MPPT. Furthermore, the fractional-order control approach was deployed in the proposed adaptive backstepping controller to provide a smooth control signal for enhancing the quality of the power injected into the grid. The stability analysis of the overall closed-loop system was performed using Lyapunov's stability theory. The high effectiveness of the proposed control method was assessed through simulation studies carried out in MATLAB/Simulink of a DFIG-wind turbine operating in various conditions.
PubDate: 2022-11-27

• Classification by Principal Component Regression in the Real and
Hypercomplex Domains

Abstract: Abstract Linear regression is a simple and widely used machine learning algorithm. It is a statistical approach for modeling the relationship between a scalar variable and one or more variables. In this paper, a classification by principal component regression (CbPCR) strategy is proposed. This strategy depends on performing regression of each data class in terms of its principal components. This CbPCR formulation leads to a new formulation of the Linear Regression Classification (LRC) problem that preserves the key information of the data classes while providing more compact closed-form solutions. For the sake of image classification, this strategy is also extended to the 4D hypercomplex domains to take into account the color information of the image. Quaternion and reduced biquaternion CbPCR strategies are proposed by representing each channel of the color image as one of the imaginary parts of a quaternion or reduced biquaternion number. Experiments on two color face recognition benchmark databases show that the proposed methods achieve better accuracies by a margin of about 3% over the original LRC and like methods.
PubDate: 2022-11-27

• Photocatalytic Performance of Organically Templated Cr-Doped Co3O4 in
Remediation of Industrial Wastewater: Effect of Order–Disorder in the
Lattice

Abstract: Abstract In photocatalysis, the optical properties and surface parameters significantly affect the catalytic performance. To engineer the optical properties and textural structure, Cr and p-phenylene diamine (PDA) were utilized as dopant and textural structure regulator, respectively. A series of Cr-doped Co3O4 with dopant percentages of 0, 1, 3, and 5, templated PDA at a fixed ratio of 5%, and another un-templated sample with a dopant ratio of 5% were prepared. The co-precipitation method was applied in swift and innovative procedures, where a calculated amount of NaOH was used as a precipitant. The optical properties, dopant concentration quenching, and surface parameters are strongly affected by the order–disorder in the lattice and dopant concentration. The lattice regularity affects the optical properties and the surface parameters along with the dopant concentration. The photocatalysts were evaluated in the disposal of organic pollutants in a representative sample of wastewater collected from different industrial activities. The function of another function was applied to monitor the pollutants' disposal, taking the total organic carbon (TOC) as a function of the pollutants' concentration and the photometric absorbance as a function of the TOC. The kinetic investigation exhibited the significant role of the pore system on the reaction rate.
PubDate: 2022-11-27

• Thermodynamic Analysis of a Reconfigured 500-MWe Supercritical Thermal
Power Plant by Integrating Solid Oxide Fuel Cell and a Gas Turbine

Abstract: Abstract In the present study, a detailed thermodynamic analysis is performed on an integrated gasification fuel cell-combined cycle (IGFC-CC), which is a reconfigured standalone 500-MWe supercritical thermal power plant. The plant is powered by the syngas obtained through gasification of Indian high ash coal. The modeling and analysis of the plants are done using a commercially available Fortran-based software program called ‘CYCLE-TEMPO.’ IGFC-CC is configured with the recirculation of anode and cathode effluents of SOFC to its respective electrode inlets. The 1st and 2nd law analysis has shown the standalone plant’s energy and exergy efficiencies to be 38.22% and 33.83%. These efficiencies are 52.83% and 46.76%, when evaluated for the proposed plant considering RR value as 0.9 of anode effluent and 20% excess air being supplied to the combustor downstream of SOFC. The exergy analysis of the standalone and proposed reconfigured plant indicates major irreversibilities are associated with the furnace and gasifier, respectively, i.e., around 33.2% and 21.6%. A comparative study between the standalone and proposed IGFC-CC plant has shown a reduction in the specific fuel consumption of the proposed plant from 0.32 to 0.54 kg/kWh of the standalone plant. The specific CO2 emission from IGFC-CC is noticed to be 0.46 kg/kWh, which is 40.4% less than emission from standalone plant apart from enhancement in the energy as well as exergy efficiencies. The economic analysis of the proposed reconfigured plant has yielded the levelized cost of electricity at Rs. 5.93/kWh.
PubDate: 2022-11-25

• Synthesis of CuO/α-Fe2O3 Nanocomposite by Q-Switched Pulsed Laser
Ablation and its Catalytic Activity for Environmental Applications

Abstract: Abstract CuO/α-Fe2O3 nanocomposites (with 0%, 5%, 10%, and 20% CuO compositions) were synthesized using a fast and clean technique called pulsed laser ablation. The products were characterized using FTIR, SEM–EDS, HR-SEM, XRPD, DR-UV-Vis, and Raman spectroscopy. The nanocomposites were evaluated as catalysts for NaBH4 reduction of 4-nitrophenol (4-NP). The catalytic efficiency was found to increase greatly with the increase in the amount of CuO in the nanocomposites. The 20% CuO/α-Fe2O3 nanocomposite shows the highest reduction efficiency of 4-NP, which completes in 6 min. The rate constants for the reduction of 4-NP using 5%, 10%, and 20% CuO/α-Fe2O3 nanocomposites were estimated to be 0.00756 mM∙min−1, 0.01375 mM∙min−1, and 0.01439 mM∙min−1, respectively.
PubDate: 2022-11-24

• An Integrated Two-Stage Inventory and Workforce Planning Model with
Variable Production Rates

Abstract: Abstract This paper addresses the economic lot-sizing and manpower planning in a two-stage manufacturing system. We refer to the first and second stages as the vendor and the manufacturer, respectively. Both the vendor and the manufacturer can operate at different production rates by varying the levels of their manpower. In Economics and Econometrics, the rate of production is usually modelled using the production function, a model which links company productivity to the level of existing resources, such as labour and capital. Namely, we utilize the Cobb–Douglas production function to represent the relationship between the production inputs (labour and capital) and the productivity. The impact of manpower planning decisions on the proposed supply chain system is studied. An efficient solution technique is proposed; then, sensitivity analysis and fractional factorial design were conducted to assess the performance of the proposed model. Our results suggest that the variable production rates may lead to substantial savings to the supply chain, especially in the case of low-profit margins. Furthermore, considering the vendor as a leader and the manufacturer as a follower in a Stackelberg sequential game, we present two contracts to share the resulting savings between the vendor and the manufacturer.
PubDate: 2022-11-24

• Double-Diffusive Unsteady Flow in a Roof-Based Air Ventilation System with
Variable Prandtl Number

Abstract: Abstract Double-diffusive mixed convection problem had been a notable topic of research in the last decade. Lack of study is noticed under mixed convection using this double-diffusive in an enclosure specifically for roof-based ventilation systems with unsteady, partially heated conditions. This study investigates the Prandtl number effect in a double-diffusive unsteady flow in a square-shaped room where the upper channel was used for ventilation, and inside the enclosure, the walls are partially heated and mass concentrated. Galerkin residual method was implemented to get the governing equations. The Prandtl number 0.071 ≤ Pr ≤ 7.1 was chosen for the study, changing the dimensionless time 0.1 ≤ τ ≤ 1. The results have been shown in the mode of graphical representation and contour plots to observe the Prandtl number effect in such problem. The velocity streamline, isotherm, isoconcentration plots, heat and mass transfer rate, average fluid temperature and average mass concentration, etc., are shown. Results showed that heat and mass transfer rise with the growth of the Prandtl number. This research would be the guide for the design consideration in such double-diffusive systems like roof-based air ventilation systems with partial heat and mass generation.
PubDate: 2022-11-24

• Estimating the Power Saving of KCOOH Liquid Desiccant Dehumidification
System Using a Statistical Method

Abstract: Abstract In hot and moist weather, a hybrid liquid desiccant dehumidification conditioning (LDAC) system is proposed as a viable substitute to stand-alone conventional vapour compression refrigeration (VCR) system because of their dominance in extracting the latent heat load from the air, being environmentally friendly, removing pollutants from the processed air, and consuming less electrical energy. The current research article experimentally investigates the dehumidification performance of a potassium formate (KCOOH) solution on an innovatively designed and developed 5-kW hybrid LDAC system. The main aim of this research paper is to optimize the performance parameters of a hybrid LDAC system employing a full factorial DOE design. The three input variables are selected to evaluate their effects on the three output performance responses. The regression correlation is obtained to anticipate the performance of the KCOOH solution for the output responses. The experimental result reveals that their improvement of 26.97% in $${\mathrm{COP}}_{{{\mathrm{Hybrid}}}}$$ as compared to a stand-alone VCR unit and that the influence of inlet desiccant concentration is more prominent than the inlet mass flow rate and inlet desiccant temperature on the output responses.
PubDate: 2022-11-24

• Design Optimization of a Fluidic Diode for a Wave Energy Converter via
Artificial Intelligence-Based Technique

Abstract: Abstract A pair of turbines can harness power from a wave energy Converter. Their performance is poor than individual turbines due to flow reversal. A fluidic diode (FD) which offers variable resistance to the flow, can be used to prevent flow reversal and improve the performance of these units. Its performance is given by diodicity (ratio of reverse to forward flow pressure drop). A higher diodicity enables it to prevent flow reversal better and improve the turbine unit’s overall efficiency. In this work, the geometrical shape of the FD is optimized to obtain higher diodicity. Six geometrical variables of the FD are varied to obtain sample points using the sampling technique, which is numerically investigated by solving steady-state Reynolds averaged Navier–Stokes (RANS) equations. These numerical results were fed into a neural network code that produced an optimal FD design. The optimum model showed a 36.5% improvement in diodicity at 0.35 m3/s. The fluid flowing through the optimized model experience higher resistance in the reverse direction because of the increased vortex strength than the base model. Among all the design variable considered, nozzle angle is a highly sensitive parameter in the optimization process. The optimum FD model enhanced the overall efficiency of the turbine unit by 13.3.
PubDate: 2022-11-23

• Review of Mechanical Properties and Damage Theory of Fiber-Reinforced
Low-Heat Cement Concrete

Abstract: Abstract Low-heat Portland cement has been extensively used in mass concrete because of its low hydration heat and high later strength. However, low-heat cement has characteristics of slow activity and low early strength, which affects its propagation and applications in mass concrete to a certain degree. Moreover, comprehensive theoretical research on the mechanical properties and constitutive relations of pure and modified low-heat cement concretes is lacking. In view of this, this study reviews the research progress of the mechanical properties and the damage theory of fiber-reinforced low-heat cement concrete based on analysis of the existing literature. First, the mineral composition, hydration mechanism, and performance characteristics of low-heat cement concrete are analyzed. Second, the performance traits of low-heat cement fiber concrete are examined, and the influence laws of basalt and brucite fibers on the mechanical properties of concrete are determined. Finally, the application of damage mechanics theory to fiber-reinforced concrete is summarized. This study shows that although fibers can effectively enhance the mechanical properties of low-heat cement concrete, there are limitations in the selection of fiber type. In addition, basalt and brucite fibers play significant roles in enhancing the mechanical properties of concrete; therefore, the objectives of this paper are to present the application prospects of fibers in low-heat cement concrete and propose a new concept of mixing fibers to boost the early mechanical properties of low-heat cement concrete. Combining theoretical research and analysis, it provides directions and concepts for applying the damage theory to low-heat fiber cement concrete in the future.
PubDate: 2022-11-23

• Biosynthesis and Analytical Characterization of Iron Oxide
Nanobiocomposite for In-Depth Adsorption Strategy for the Removal of Toxic
Metals from Drinking Water

Abstract: Abstract The biosynthesis of the iron oxide nanoparticles was done using Ixoro coccinea leaf extract, followed by the fabrication of iron oxide nanobiocomposites (I-Fe3O4-NBC) using chitosan biopolymer. Furthermore, the synthesized I-Fe3O4-NPs and I-Fe3O4-NBC were characterized, and I-Fe3O4-NBC was applied to remove toxic metals (TMs: Cd, Ni, and Pb) from water. The characterization study confirmed that the nanostructure, porous, rough, crystalline structure, and different functional groups of chitosan and I-Fe3O4-NPs in I-Fe3O4-NBCs showed their feasibility for the application as excellent adsorbents for quantitative removal of TMs. The batch mode strategy as feasibility testing was done to optimize different adsorption parameters (pH, concentrations of TMs, dose of I-Fe3O4-NBC, contact time, and temperature) for maximum removal of TMs from water by Fe3O4-NBC. The maximum adsorption capacities using nanocomposites for Cd, Ni, and Pb were 66.0, 60.0, and 66.4 mg g−1, respectively. The adsorption process follows the Freundlich isotherm model by I-Fe3O4-NBC to remove Cd and Ni, while the Pb may be adsorption followed by multilayer surface coverage. The proposed adsorption process was best fitted to follow pseudo-second-order kinetics and showed an exothermic, favorable, and spontaneous nature. In addition, the I-Fe3O4-NBC was applied to adsorption TMs from surface water (%recovery > 95%). Thus, it can be concluded that the proposed nanocomposite is most efficient in removing TMs from drinking water up to recommended permissible limit.
PubDate: 2022-11-23

• Developing Climate Classification for Oman Using Degree-Days Method

Abstract: Abstract Local climate classification is mandatory for building energy standards and codes. The degree-days method is one of the most widespread methods used for climate classification. Many degree-days models are available for determining the cooling degree days (CDD) and the heating degree days (HDD). A limited number of studies have been conducted to evaluate the performance of these models in cooling-dominated climates, which is mandatory before a model is adopted for climate classification. In this research, five models, namely the hourly method, ASHRAE method, Erbs method, Schoenau and Kehrig (S-K) method, and hybrid S-K method, were evaluated and analyzed for predicting CDD and HDD. Hourly data from selected meteorological stations located in different regions of Oman were used. The results indicated that the performance of all models was acceptable and within 10% variation from the hourly method, with the hybrid S-K model being the best among all models. This model was then used to estimate the CDD and HDD for 31 weather stations in Oman using the monthly average temperature data. Regression models were then developed for CDD and HDD at different base temperatures, with determination coefficient, R2, of higher than 99%, maximum error of 4.9, and − 0.217% for CV[RMSE] and NMBE, respectively. Using the GIS ArcMap, the CDD values were used to generate the climate classification for Oman. Subsequently, four climate zones were identified, namely hot-humid climate, hot-dry climate, warm-humid climate, and high-altitude climate. The developed climate classification is useful and can be used for building energy efficiency programs, standards, and codes.
PubDate: 2022-11-23

• A Novel Approach for Semi-supervised Learning: Incremental Parallel
Training with Cross-Validation (IPT-CV)

Abstract: Abstract There are plenty of unlabeled data in different domains, and effective ways that apply machine learning techniques are in dire need to be found for the ability to use them efficiently. Semi-supervised learning methods are utilized to extract useful information from these unlabeled data. In our study, the Incremental Parallel Training with Cross-Validation (IPT-CV) method is proposed as a novel semi-supervised learning method. This proposed method employs several classifiers and different views of the datasets to label the unlabeled data in an efficient manner. The classifiers used in the algorithm work in parallel each round and enlarge the labeled set according to a validation rule. The method was compared with two well-known SSL methods in the literature. The web was chosen as the domain of the experiments, since it is a land of unlabeled files. Nine binary classification datasets were used from the publicly available WebKB, Banksearch, and the individually collected Conference datasets. The results were statistically analyzed, and according to these analyses, the proposed IPT-CV method showed the highest classification accuracy among all of the methods that were examined.
PubDate: 2022-11-23

• Dynamic Characterization of MR Fluid-Based Dynamic Vibration Absorber

Abstract: Abstract A magnetorheological (MR) damper is effective and economical for miscellaneous applications in automotive, mechanical, civil, and relative fields. A parameter tuning methodology independent of manual trial-and-error has received much technical interest for controlling vibrations. The present work contributes mathematical and Simulink modeling followed by MR damper design and development for vibration optimization of the single degree of freedom system. A Simulink model of an MR damper is performed on the mathematical model for vibration control, and the MR damper’s tuning parameters are experimentally investigated to control the resonance frequency. Theoretical simulated results and its experimental verification show that increasing current raises the force to control the resonance frequency in an MR damper. The present approach provides a concise and improved platform for dynamic vibration absorber in the current potential market and the highly interested control community for the development of the distinctive attributes of the MR Damper.
PubDate: 2022-11-22

• Dynamic Simulation and Experiment of Marching Small Unmanned Ground
Vehicles with Small Arms

Abstract: Abstract To research the muzzle response characteristics of marching small unmanned ground vehicles with small arms (SUGVsSA), this paper establishes a launch dynamic model of an SUGVSA by considering various nonlinear features. According to the mechanism characteristics, the improved Lankarani–Nikravesh algorithm is adopted to define the projectile–barrel coupling effect and trunnion–bearing clearance collision behaviour; additionally, the collision models of bearing race and worm gear are both established by the Hertz contact theory. Muzzle vibration experiments based on the combination of high-speed photogrammetry and inertial measurement systems are performed to verify the accuracy of the SUGVSA launch dynamic model. Three-dimensional (3D) road shell models are established by using the harmonic superposition method and then discretized and integrated with the Bekker soil mechanical properties to generate a flexible 3D road surface. The muzzle response characteristics of the SUGVSA under various working conditions are calculated and analysed. The results indicate that the muzzle response characteristics are related to the road shell, soil type, and driving speed, and they present many regularities. The initial firing angle has no obvious effect on the muzzle response. If the clearance between the trunnion and bearing increases, the muzzle elevation angular vibration intensifies when the SUGVSA moves. The muzzle aim point deviation caused by the flexible barrel is small, and it is not the main factor affecting the shooting accuracy of marching SUGVsSA. The muzzle vertical stabilizer can reduce the muzzle disturbance effectively, but the stabilization effect based on the PID system is not ideal. It is necessary to propose a more robust control algorithm to improve the muzzle stabilization accuracy.
PubDate: 2022-11-22

• Maximum Concurrent Flow Solutions for Improved Routing in IoT Future
Networks

Abstract: Abstract Due to the advent of IoT and the increasing interest of billions of Internet users towards video contents, a huge multimedia flows has been generated, and as a consequence, a massive load is applied on the underlying core network. This change can affect the network stability and lead to potential performance degradation (such as congestion and delays). This is because multimedia flows are hungry in bandwidth, and also the classical routing protocols currently used in IoT core network (like OSPF) are not adapted yet to support the heavy and the large scale of multimedia traffics with a good quality of service (QoS). In this paper, we introduce the multicommodity-based routing by proposing two contributions, Maximum Concurrent Flow Protocol (MCFPr) and Cache-based Maximum Concurrent Flow (C-MCF). They are conceived based on the Maximum Concurrent Flow approach in order to optimize the routing of multimedia data in the backbone of IoT networks. Both contributions are studied and compared with the state-of-art approaches under different scenarios showing good results, especially in the number of data packets sent (improvement by 50%), and in the transmission time (50% faster compared to the majority), which makes them promising solutions for a rapid and efficient routing in IoT core networks.
PubDate: 2022-11-22

• Stability Analysis and Implementation of a Wheel-Leg Robot Using the
Force-Angle Method

Abstract: Abstract Considering that stability is an inseparable part of mobile robots, in this paper, the stability of a wheeled-legged robot is investigated. A suitable method for stability analysis should be adopted regarding the robot mechanism and alteration in its height. One of the critical issues in this regard is the displacement of the center of mass for various reasons, such as the manipulator displacement or uncertainties in the robot mechanism. Thus, this paper brings novelty by considering a parameter for the position of the center of mass relative to the geometric center of the robot, which has not yet been discussed as an independent degree of freedom. In this regard, due to its ability to extend in three dimensions and determination of the applied torques according to the variable height of the robot, we propose a novel force-angle method That has been selected and applied for stability analysis. While a specific variable is defined for the relative position of the center of mass, which generalizes this stability method. Then, to validate the extended Force-Angle method, the theoretical results are compared with the obtained results of the constructed WLRIUST robot. The range of stability of the robot was determined at different points of the center of mass and with possible angles for the legs of the robot, and the torques were reported because torque jumps are an important factor in system instability. Hence, These results are also theoretically and practically compared concerning changes in joint torques when the robot is unstable.
PubDate: 2022-11-22

• Composition Optimization of Iron-Nickel-Nanographite Particles for Tuning
the Electromagnetic Parameters of Silicone Rubber Composites

Abstract: Abstract The current study investigates iron (Fe)-nickel (Ni)-nanographite (NG) / silicone rubber composites for improved microwave absorption in 8–18 GHz range. Fe–Ni particles were produced in three different ratios (50:50, 60:40, and 75:25) using high-energy planetary ball mill. NG was also prepared from graphite using wet milling. The Fe–Ni combinations were then ball milled with NG at 75:25 ratio (Fe–Ni: NG) and coded as (Fe0.75Ni0.25)0.75NG0.25, (Fe0.6Ni0.4)0.75NG0.25, and (Fe0.5Ni0.5)0.75NG0.25. These hybrid nanoparticles were investigated for their structural and morphological properties. The thermomechanical, environmental and electromagnetic properties of silicone rubber composites with these nanoparticles (20% w/w) were studied. Around 60% improvement in tensile strength with 40% more elongation is achieved compared to the pure silicone rubber samples. (Fe0.5Ni0.5)0.75NG0.25 based sample shows good dynamic mechanical properties with almost 4 times increase in storage modulus and twice increase in loss modulus from − 20 °C to room temperature. The conducting nature of hybrid nanoparticles helps to reduce the electrical impedance up to two orders (from 104 to 102 Ω). The composites with (Fe0.75Ni0.25)0.75NG0.25 have excellent mechanical characteristics and good dielectric and magnetic loss while the electromagnetic characteristics of (Fe0.6Ni0.4)0.75NG0.25 based composites have shown greater broad-spectrum absorption in 8–18 GHz range. Real and imaginary permittivity values are up to 50 and 8, respectively while real and imaginary permeability values are around 1 and 0.5, respectively. The results indicate that these flexible polymer nanocomposite sheets are a viable contender as microwave absorbers in a variety of stealth applications over wide range environmental conditions.
PubDate: 2022-11-22

• Phytochemical Characterization and Bioefficacy Studies of Blastania
cerasiformis and Blastania garcinii for Antioxidant, Antidiabetic,
Anticancer and Antimicrobial Activities

Abstract: Abstract Blastania species are neglected, unexplored and ethanomedicinaly important wild cucurbits. The present study was conducted to explore nutraceutical potential of two Blastania species that is Blastania cerasiformis (Stocks) A. Meeuse and Blastania garcinii (Burm.f.) Cogn. The study was extensively carried out with different plant parts (leaves, unripened fruits, ripened fruits) extracted with solvents (acetone, ethanol, methanol, water). The results highlighted the highest nutritional potential from B. cerasiformis ripened fruits with an energy value (268 ± 1.06 kcal/100 g). Phytochemical analysis revealed the excellency of unripened fruits for high phenolic, flavonoid, tannin, terpenoid and alkaloid content. Antioxidant assays highlighted the antioxidant richness of fruits of Blastania species than leaves. B. garcinii leaves acetone extract was found efficient for the maximum α-amylase inhibition (68.83%) and α-glucosidase inhibition (35.06%) activities. The maximum anticancer activity was recorded from B. cerasiformis ripened fruits (IC50 39.21 µg/ml). Blastania species have exhibited significant antimicrobial activity (0.1–4.0 mm) against 11 human pathogenic microbes. Fatty acid profiling revealed the presence of 24 fatty acids from Blastania species. GC–MS analysis of methanolic extracts recorded 43 bioactive compounds having wide range of biological properties. Principal component analysis exhibited a positive correlation between tested phytochemical, antioxidant and antidiabetic activities. The results have significantly proven the medicinal potential of Blastania species against reactive oxygen species, diabetes, cancer and human pathogenic microbes. Further detailed study is needed to establish Blastania species as a novel source of nutraceutical and medicinal drugs.
PubDate: 2022-11-21

• New Effective Method for Identification of Coal and Roof Interface Based
on Cutting Performance

Abstract: Abstract Shearer is an essential equipment in mechanized coal mining process. Roof cutting often turns up for shearer during working process, leading to extra vibration on shearer and reducing its service life. Coal and rock interface recognition is a fundamental technical way for shearer to avoid continuous roof cutting. In this paper, an effective method for coal and rock interface is proposed and it is mainly based on the cutting loads on shearer drum in three different kinds of working states. The constitutions of cutting force on shearer drum are analyzed under conditions of different proportions of rock thickness in the cutting range and then model for calculation of cutting force in the coal–rock mixed seam are proposed which is a function of rock proportion in the cutting range. To verify the model, hard roof with different material strengths and different interfaces are established with the numerical method and rock proportions in the cutting range are derived based on the mentioned method. In terms of the situations where rock material properties are close to coal and the results are obtained with lower accuracy, enlarging the difference of rock proportions in the second and third states is proposed and the relations between the recognition accuracy and the differences of rock proportions in different states are explored as well. The results show that the estimation method works well with qualititative analysis of coal and roof interface even if coal and rock material properties are various and not able to be known in advance. In addition, the adjustment height of shearer drum is the important factors highly related with the estimation accuracy and it would be helpful for accuracy improvement in conditions where the material properties of coal and roof are closer to each other or larger roof cutting thickness happens in coal mining. The method provides the possibility for qualititative analysis of coal and roof interface with easy accessibility and wide adaptability.
PubDate: 2022-11-21

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