Influence of B4C and ZrB2 reinforcements on microstructural,mechanical and wear behaviour of AA 2014 aluminium matrix hybrid composites

Considering their affordability and high strength-to-weight ratio,lightweight aluminium alloys are the subject of intensive research aimed at improving their properties for use in the aerospace industry.This research effort aims to develop novel hybrid composites based on AA 2014 alloy through the use of liquid metallurgy stir casting to reinforce dual ceramic particles of Zirconium Diboride(ZrB_(2))and Boron Carbide(B4C).The weight percentage(wt%)of ZrB_(2) was varied(0,5,10,and 15),while a constant 5 wt%of B4C was maintained during this fabrication.The as-cast samples have been assessed using an Optical Microscope(OM)and a Scanning Electron Microscope(SEM)with Energy Dispersive Spectroscopy(EDS).The properties such as hardness,tensile strength,and wear characteristics of stir cast specimens were assessed to examine the impact of varying weight percentages of reinforcements in AA 2014 alloy.In particular,dry sliding wear behaviour was evaluated considering varied loads using a pin-on-disc tribotester.As the weight%of ZrB_(2) grew and B4C was incorporated,hybrid composites showed higher hardness,tensile strength,and wear resistance.Notably,the incorporation of a cumulative reinforcement consisting of 15 wt%ZrB_(2) and 5 wt%B4C resulted in a significant 31.86%increase in hardness and a 44.1%increase in tensile strength compared to AA 2014 alloy.In addition,it has been detected that wear resistance of hybrid composite pin(containing 20 wt%cumulative reinforcement)is higher than that of other stir cast wear test pins during the whole range of applied loads.Fractured surfaces of tensile specimens showed ductile fracture in the AA 2014 matrix and mixed mode for hybrid composites.Worn surfaces obtained employing higher applied load indicated abrasive wear with little plastic deformation for hybrid composites and dominant adhesive wear for matrix alloy.Hence,the superior mechanical and tribological performance of hybrid composites can be attributed to dual reinforcement particles being dispersed well and the effective transmission of load at this specific composition.

Effects of Substrate Permeation on Kinetics of Phenol Biodegradation

Based on the theory of substrate permeation through the cytoplasmic membrane,and considering the effect of initial concentration of substrate,a new kinetic model of phenol degradation process was proposed,Comparing with the widely used Haldane model,which is greatly dependent on the initial phenol concentration,our model can be used to simulate the phenol degradation process in a wide range of initial phenol concentration by using only one set of model parameters ,Therefore,this new kinetic model has much more potential applications to industrial design and operation.

SIMPLE SIMULATION OF THE ANNUAL VARIATION OF THE SPECIFIC PHOTOSYNTHESIS RATE IN JIAOZHOU BAY

A simple diagnostic simulation of the annual cycling of the surface specific photosynthesis rate (SPR) in Jiaozhou Bay is described in this paper. Light intensity, temperature and nutrients (nitrate + ammonia, phosphate) were considered as main factors controlling photosynthesis of phytoplankton and were introduced into the model by different function equations. The simulated variation of specific photosynthesis rate coincided with the measured data. Analysis of the effect of every factor on photosynthesis indicated that the variation of photosynthesis rate was controlled by all these three factors, while temperature showed good correlation with SPR as measurement showed. This diagnostic simulation yielded the values of some parameter relating with the photosynthesis in Jiaozhou Bay.

Measurement Analysis of Specific Absorption Rate in Human Body Exposed to a Base Station Antenna by Using Finite Difference Time Domain Techniques

The system analysis of specific absorption rate(SAR)in human body ex­posed to a base station antenna by using finite difference time domain tech­niques was presented in this research works.The objectives of this work are to evaluate the knowledge and awareness about SAR among human body and mobile base station.The paper investigates the electromagnetic wave absorption inside a human body.The human body has been identified us­ing dataset based on 2D object considering different electrical parameters.The SAR convinced inside the human body model exposed to a radiating base station antenna(BSA)has been considered for multiple numbers of carrier frequencies and input power of 20 W/carrier at GSM 900 band.The distance(R)of human body from BSA is varied in the range of 0.1 m to 5.0 m.For the number of carrier frequency equal to one and R=0.1 m,the concentrated value of whole-body average SAR obtained by FDTD technique is found to be 0.68 W/kg which decreases either with increase of R or decrease of number of carrier frequencies.Safety distance for general public is found to be 1.5 m for number of carrier frequencies equal to one.The performance accuracy of this analysis meets the high level condition by comparing with the relevant system development in recent time.

Higher Order OAM Mode Generation Using Wearable Antenna for 5G NR Bands

This paper presents a flexible and wearable textile array antenna designed to generate Orbital Angular Momentum(OAM)waves with Mode+2 at 3.5 GHz(3.4 to 3.6 GHz)of the sub-6 GHz fifth-generation(5G)New Radio(NR)band.The proposed antenna is based on a uniform circular array of eight microstrip patch antennas on a felt textile substrate.In contrast to previous works involving the use of rigid substrates to generate OAM waves,this work explored the use of flexible substrates to generate OAM waves for the first time.Other than that,the proposed antenna was simulated,analyzed,fabricated,and tested to confirm the generation of OAMMode+2.With the same design,OAM Mode−2 can be generated readily simply by mirror imaging the feed network.Note that the proposed antenna operated at the desired frequency of 3.5 GHz with an overall bandwidth of 400 MHz in free space.Moreover,mode purity analysis is carried out to verify the generation of OAM Mode+2,and the purity obtained was 41.78%at free space flat condition.Furthermore,the effect of antenna bending on the purity of the generated OAM mode is also investigated.Lastly,the influence of textile properties on OAM modes is examined to assist future researchers in choosing suitable fabrics to design flexible OAM-based antennas.After a comprehensive analysis considering different factors related to wearable applications,this paper demonstrates the feasibility of generating OAMwaves using textile antennas.Furthermore,as per the obtained Specific Absorption Rate(SAR),it is found that the proposed antenna is safe to be deployed.The findings of this work have a significant implication for body-centric communications.

Optimal Light Intensity and Nitrogen-to-Phosphorus Ratio for Growth of Nitzschia capitellata Hust.

Objective] The aim was to explore the potential of Nitzschia capitel ata as excel ent baits and bioenergy, and the optimal light intensity and nitrogen-to-phos-phorus （N/P） ratio suitable for its growth were researched as wel . [Method] With light intensity gradient set, Nitzschia capitel ata was cultured with the same nutrients at （25 ±1） ℃ and light cycle at 12 h/d to select optimal light intensity. Then, Nitzschia capitel ata was cultured with the same condition, and nitrogen-to-phospho-rus ratios at 5∶1, 6∶1, 7∶1 and 8∶1. [Result] With light intensity at 3 000 lx, specific growth rate and standing stock achieved the highest at 0.51 d-1 and 7.97×104 cel s/ml. The growth condition with nitrogen-to-phosphorus ratio at 6∶1 was the most suitable for Nitzschia capitel ata growth. [Conclusion] The optimal light intensity and nitrogen-to-phosphorus ratio were 3 000 lx and 6∶1, respectively, for Nitzschia capitel ata.

Calculation of Electromagnetic Field and SAR Dis- tributions of Two Antenna Structures for Bone Tu- mors Microwave Hyperthermia

Objective: To investigate the electromagnetic field and specific absorptionrate (SAR) distribution of different structure applicators with different depths for treating bonetumors using microwave hyperthermia. Methods: The finite element method (FEM) was used to calculate,electromagnetic field and SAR distribution. Two different structure applicators were simulated. Theone is simple coaxial antenna, which has been successfully used in clinic treating bone tumors inTangdu hospital of the Forth Military Medical University several years. It was formed by a coaxialcable peeled off the out copper at end. The other applicator was coaxial- slot antenna, which waswidely used in microwave hyperthermia. The applicator inserted into the cylindrical bone withdifferent depths, and worked at the frequency of 2 450 MHz. Results: The electric field and SARgenerated by the simple coaxial applicator were mainly concentrated out the tissues, and were notuniform in the tissues, while the coaxial- slot applicator well transmits the electric field and SARinto the tissues, and can easily treat different position by adjusting the slat position.Conclusion: The results calculated by EFM, were well accordant with the experimental and clinicalresulls, and will be important for improving the clinical effects of microwave hyperthermia.

Effects of salinity and nutrients on the growth and chlorophyll fluorescence of Caulerpa lentillifera

Caulerpa lentillifera is a green algae that distributes worldwide and is cultivated for food. We assessed vegetative propagation of C. lentillifera by measuring the specific growth rate （SGR） and chlorophyll fluorescence of the green algae cultured at different salinities and nutrient levels. The results indicated that C. lentillifera can survive in salinities ranging from 20 to 50, and can develop at salinities of 30 to 40. The maximum SGR for C. lentillifera occurred at a salinity of 35. Both chlorophyll content and the ratio of variable to maximum fluorescence （F_v/F_m） were also at a maximum at a salinity of 35. Photosynthesis was inhibited in salinities greater than 45 and less than 25. Both the maximum SGR and maximum chlorophyll content were found in algae treated with a concentration of 0.5 mmol/L of NO3-N and 0.1 mmol/L of PO_4-P. The photosynthetic capacity of photosystem Ⅱ （PSⅡ） was inhibited in cultures of C. lentillifera at high nutrient levels. This occurred when NO_3-N concentrations were greater than 1.0 mmol/L and when PO4-P concentrations were at 0.4 mmol/L. As there is strong need for large-scale cultivation of C. lentillifera, these data contribute important information to ensure optimal results.

Conversion regular patterns of acetic acid,propionic acid and butyric acid in UASB reactor

On the basis of continuous tests and batch tests, conversion regular patterns of acetate, propionate and butyrate in activated sludge at different heights of the UASB reactor were conducted. Results indicated that the conversion capacity of the microbe is decided by the substrate characteristic when sole VFA is used as the only substrate. But when mixed substrates are used,the conversion regulations would have changed accordingly. Relationships of different substrates vary according to their locations. In the whole reactor, propionate's conversion is restrained by acetate and butyrate of high concentration. On the top and at the bottom of the reactor, conversion of acetate, but butyrate, is restrained by propionate. And in the midst, acetate's conversion is accelerated by propionate while that of butyrate is restrained. It is proved, based on the analysis of specific conversion rate, that the space distribution of the microbe is the main factor that affects substrates' conversion. The ethanol type fermentation of the acidogenic phase is the optimal acid type fermentation for the two phase anaerobic process.

Re-activation characteristics of preserved aerobic granular sludge

In some industrial plants, wastewater was intermittently or seasonally generated. There may be periods during which wastewater treatment facilities have to be set into an idle phase over several weeks. When wastewater was generated again, the activated sludge flocs may have disintegrated. In this experiment, re-activation characteristics of aerobic granular sludge starved for 2 months were investigated. Specific oxygen utilization rate(SOUR) was used as an indicator to evaluate the metabolic activity of the sludge. The results revealed that aerobic granular sludge could be stored up to two months without running the risk of losing the integrity of the granules and metabolic potentials. The apparent color of aerobic granules stored at room temperature gradually turned from brownish-yellowish to gray brown. They appeared brownish-yellowish again 2 weeks after re-activation. The velocity and strength of granules after 2-month idle period could be fully restored about 3 weeks after re-activation. Metabolic activity, however, dropped to 15 8 mg O_2/(g MLVSS·h), i.e. 74 % reduction after 2 months of storage. After restarting the reactor, it took 2 weeks that SOUR of up to 48 5 mg O_2 /(g MLVSS·h) was achieved. A stable effluent COD concentration of less than 150 mg/L was achieved during the re-activation process.

Phase separation in solvent extraction of cobalt from acidic sulfate solution using synergistic mixture containing dinonylnaphthalene sulfonic acid and 2-ethylhexyl 4-pyridinecarboxylate ester

Phase separation rate is a critical character in determining the usefulness of a solvent extraction system in hydrometallurgy. A survey of the synergistic mixture containing dinonylnaphthalene sulfonic acid (HDNNS) and 2-ethylhexly 4-pyridinecarboxylate ester (4PC) for the extraction of cobalt from acidic single metal sulfate solution was carried out to suggest how the physicochemical properties and the morphology of the reverse micelles in the loaded organic phase affect the phase separation. The results show that effective parameters affecting the phase separation are the viscosity and the excess water uptake of the loaded organic phase. It is obvious that the specific settling rate (SSR) decreases with the apparent increase of these two parameters. The measurement of small angle X-ray scattering (SAXS) proves that the morphology of the reversed micelles in the loaded organic phase changes evidently with the change of the specific settling rate (SSR).

Comparative Studies on Phosphorus Uptake and Growth Kinetics of the Microalga Tetraselmis subcordiformis and the Macroalga Ulva pertusa

Short term uptake experiments and long term semicontinuous culture experiments were performed under the condition of phosphorus (P) limitation to estimate and compare the P uptake and growth kinetics of the microalga Tetraselmis subcordiformis and the macroalga Ulva pertusa. Two new parameters, the maximum specific uptake rate ( V sp m) and the maximal growth efficiency ( β ), are introduced to achieve uniformity for the comparison of nutrient uptake and growth efficiency between microalgae and macroalgae. T. subcordiformis possesses 3 times lower half saturation uptake constant, 4 times higher maximal growth rate and 20 times higher maximum specific uptake rate than U. pertusa, while U. pertusa possesses 4 times higher maximal growth efficiency than T. subcordiformis.

Investigation of artifacts by mapping SAR in thermoacoustic imaging

Microwave-induced thermoacoustic imaging(MI-TAI)remains one of the focus of attention among biomedical imaging modalities over the last decade.However,the transmission and dis-tribution of microwave inside bio-tissues are complicated,thus result in severe artifacts.In this study,to reveal the underlying mechanisms of artifacts,we deeply investigate the distribution of specific absorption rate(SAR)inside tissue-mimicking phantoms with varied morphological features using both mathematical simulations and corresponding experiments.Our simulated results,which are confirmed by the associated experimental results,show that the SAR distri-bution highly depends on the geometries of the imaging targets and the polarizing features of the microwave.In addition,we propose the potential mechanisms including Mie-scattering,Fabry-Perot-feature,small curvature effect to interpret the diffraction effect in different scenarios,which may provide basic guidance to predict and distinguish the artifacts for TAI in both fundamental and clinical studies.

Effects of salinities on the growth and nutrient composition in the muscle of Exopalaemon carinicauda

The effect of salinity on the growth and muscle nutritional quality of theExopalaemon carinicauda was studied through testing the survival rate, specific growthrate, muscle nutrient composition, amino acid composition and content by the culturingin different salinities(0-30).The results showed that the survival rate of salinity (0-30)had no significant difference (P>0.05), and the specific growth rates at salinity 15 andsalinity 20 were significantly higher than others(P>0.05); the muscle moisture contentand the crude fat content significantly decreased(P<0.05), while the muscle crudeprotein content significantly increased with an increase in the environment salinity from0 to 30(P <0.05).The crude ash content with salinity increase had a slight increase; themuscle crude protein content (18.2) at salinity 15 was significantly higher than that atsalinity 0,5, or 10(P <0.05), but there was no significant difference between salinity 15and salinity 20(P>0.05). No significant difference was found in total amino acid contentor total essential amino acid content from salinity 0 to 30(P>0.05). Total delicious aminoacid content at salinity 15-30 was significantly higher than those at salinity 0-10(P<0.05), while there was no significant difference from salinity 15 to 30(P>0.05). Theresults suggest that the suitable salinity for muscle nutritive value ranges from 15 to 30,and the Exopalaemon carinicauda can potentially be cultured above the salinity 15.

Processing of measurement while drilling data for rock mass characterization

The information extracted from monitoring of rotary blasthole drills helps to optimize the overall mining operation. Rock hardness, drillability, blastability and specific energy of drilling are examples of parameters that have been estimated in the past using measurement while drilling techniques. In order to be able to properly utilize measurement while drilling techniques, it is important to properly collect, analyze and interpret extracted data. This paper deals with processing of measurement while drilling data such as rate of penetration, rotary speed, rotary torque and pulldown force collected from rotary blasthole drills.Different methods are discussed to calculate a true rate of penetration which is the most important monitored drill variable for use in rock mass characterization. Then specific energy of drilling is defined and calculated based on electrical and mechanical inputs and the results are compared. The results show that specific energy of drilling can be estimated using the drill's primary drive systems' electrical responses with good accuracy when compared to values based on mechanical inputs.

Approaching Complexity: Hyperthermia Dose and Its Possible Measurement in Oncology

A heuristic stochastic solution of the Pennes equation is developed in this paper by applying the self-organizing, self-similar behaviour of living structures. The stochastic solution has a probability distribution that fits well with the dynamic changes in the living objects concerned and eliminates the problem of the deterministic behaviour of the Pennes approach. The solution employs the Weibull two-parametric distribution which offers satisfactory delivery of the rate of temperature change by time. Applying the method to malignant tumours obtains certain benefits, increasing the efficacy of the distortion of the cancerous cells and avoiding doing harm to the healthy cells. Due to the robust heterogeneity of these living systems, we used thermal and bioelectromagnetic effects to distinguish the malignant defects, selecting them from the healthy cells. On a selective basis, we propose an optimal protocol using the provided energy optimally such that molecular changes destroy the malignant cells without a noticeable effect on their healthy counterparts.

Electromagnetic and Thermal Simulations of Human Neurons for SAR Applications

The impact of the electromagnetic waves (EM) on human neurons (HN) has been under investigation for decades, in efforts to understand the impact of cell phones (radiation) on human health, or radiation absorption by HN for medical diagnosis and treatment. Research issues including the wave frequency, power intensity, reflections and scattering, and penetration depths are of important considerations to be incorporated into the research study. In this study, computer simulation for the EM exposure to HN was studied for the purpose of determining the upper limits of the electric and magnetic field intensities, power consumption, reflections and transmissions, and the change in temperature resulting from the power absorption by human neurons. Both high frequency structural simulators (HFSS) from ANSYS software, and COMSOL multi-physics were used for the simulation of the EM transmissions and reflections, and the temperature profile within the cells, respectively. For the temperature profile estimation, the study considers an electrical source of 0.5 watt input power, 64 MHz. The EM simulation was looking into the uniformity of the fields within the sample cells. The size of the waveguide was set to be appropriate for a small animal model to be conducted in the future. The incident power was fully transmitted throughout the waveguide, and less than 1% reflections were observed from the simulation. The minimum reflected power near the sample under investigation was found to be with negligible reflected field strengths. The temperature profile resulting from the COMSOL simulation was found to be near 0.25 m°K, indicating no change in temperature on the neuro cells under the EM exposure. The paper details the simulation results for the EM response determined by HFSS, and temperature profile simulated by COMSOL.

A four spiral slots microstrip patch antenna for radiotelemetry capsules based on FDTD

Antenna is very crucial to radiotelemetry capsules which can measure the physiological parameters of the gastroin- testinal (GI) tract. The objective of this paper is to design a novel spiral slots microstrip patch antenna for the radiotelemetry capsules communicating with external recorder at 915 MHz located in ISM (Industry, Science, and Medical) bands. The microstrip patch antenna is designed and evaluated using the finite-difference time-domain (FDTD) method. Return loss characteristics and the effect of the human body on resonant frequency are analyzed, and the performances of radiation patterns at different positions of the human alimentary tract are also estimated. Finally, specific absorption rate (SAR) computations are performed, and the peak 1-g and 10-g SAR values are calculated. According to the peak SAR values, the maximum delivered power for the designed antenna was found so that the SAR values of the antenna satisfy the ANSI (American National Standards Institute) limitations.

Investigation of a Novel Compact Microstrip Antenna for Radiotelemetry Capsules Based on FDTD

The objective of this paper is to design a microstrip patch antenna for the miniature electro-capsule communicating with external recorder at 915MHz located in Industry, Science, and Medical (ISM) bands. Microstrip antenna design parameters, resonance characteristics and radiation patterns are evaluated using the finite-difference time-domain (FDTD) method. The effects of location of feed point and human body are analyzed, and the radiation performances of the proposed antenna are estimated in terms of radiation patterns. Finally, specific absorption rate (SAR) computations are also performed, and the peak 1-g and 10-g SAR values are calculated. According to peak SAR values, the maximum delivered power for the designed antenna was found so that the SAR values of the antennas satisfy ANSI limitations.

Impacts of Date Palm Seeds （Phoenix dactyliferous L.） on Growth Indices and Nutrient Utilization of Common Carp Cyprinus carpio L,

This study was carried out to study the effect of adding different levels of date palm seed （Phoentix dactyliJProus） powder in the diet of common carp （Cyprinus carpio） at fish laboratory of Animal Production Department, College of Agricultural Sciences, Sulaimani University, Sulaimani, Iraq. The actual experimental feeding trials were conducted for 70 d and the adaptation period for 21 d. A total of 81 common carp fingerlings weighted 62 ± 2 g were divided into three experimental groups. The control treatment T1 was with 0 g date palm seed, T2 with 2.5 g date palm seed per kg diet and T3 with 5 g date palm seed per kg diet. Each treatment was in three replicates in which three common carp fingerlings were stocked in each aquarium which fed the experimental diets twice daily. The results indicated that weight gain （WG） and specific growth rate （SGR） in the third treatment （T3） group were significantly higher than those of fish fed control diets. T2 consumed more diet than other treatments with 306.940 g with higher feed conversion ratio （FCR）; T3 was higher significantly in food efficiency. No significant （P 〈 0.05） differences obtained from consumed protein while the protein efficiency ratio was significantly higher in T3 with 319.323. Control was higher significantly in flesh weight without viscera with the third treatment; in flesh weight without head and viscera each the control and the second treatment was significantly higher than the third treatment. As a conclusion, the date palm seeds powder have a positive effect on growth performance of common carp.