The transporting of sediments across watershed systems and their placement in reservoirs causes expensive issues for the operators of dams in many different nations throughout the world. In addition to the reservoir's functional capacity steadily decreasing as sediment settles in it, silt removal is a sensitive and challenging process that frequently necessitates taking the reservoir out of service, which is practically unachievable in dry and semi-arid regions. De-silting by hydraulic dredging has recently become a necessity to increase their longevity. But during this operation there are load loss exists so it is necessary to find solutions to reduce it. The present paper revealed that use the Sodium Tripolyphosphate as a reducing agent of the friction factor during the hydraulic dredging of dams. To carry out this study, a rheumatic characterization of dams sediments and dams sediments -sodium tripolyphosphate mixtures was carried out using a torque controlled rheometer (Discovery Hybrid Rheometer DHR2 from TA instrument). The flow curves as a function of dose of sodium tripolyphosphate added to dam sediments were analysed by the modified Cross model. It is clearly shown, in this work, when the quantity of sodium tripolyphosphate is less than of 0.4 % causes a decrease in the yield stress, the zero shear rate viscosity (lower Newtonian plateau) and the infinite shear rate viscosity (upper Newtonian plateau). However, when dose of sodium tripolyphosphate is greater than the critical dose, the the yield stress, the zero shear rate viscosity (lower Newtonian plateau) and the infinite shear rate viscosity (upper Newtonian plateau) are increased. As a result, this study find that the increase on thixotropic behavior of dams sediments is occurred by the addition of sodium tripolyphosphate in a concentration ranging between 0.2 wt% and 0.8 wt% to 40 wt% and 45 wt% of dams sediments. The study also demonstrated that adding of 0.4 wt% of sodium tripolyphosphate to 40 wt% and 45 wt% dam sediments decreased the friction factor by 96% and 25% respectively.
In previous research problem statement occur in hardness to reach the thermal flux between surfaces during movement. The aim of the present investigation has been conducted to study the thermal behavior of ceramic Al2O3 (AL-99) coated on a low carbon steel type 1.0060 by using a thermal flame spray technique. The key methods used is microstructural characterization and comparing between experimental data record and numerical program.SEM showed that the Al2O3 coatings have a dense microstructure, lamellar morphology and complex of several phases. The XRD analysis of the coating after the spray showed a majority phase of α -Al2O3 rhombohedral structure and secondary phase of γ-Al2O3 orthorhombic structure. The experimental data recorded From wear indicate two step, first one corresponds to the phase of accommodation between surfaces (samples/ disc), the contact temperature gradually increases to a value Of 75 °C for both pairs, the second step , we could remark from experimental and numerical simulation, it reach 95°C for experimental test and 85 for numerical model.The important findings in tribological results showed that the temperature at the contact is related to the shear stress that will result from the increase of the heat flux. From these results it can be said that the measured temperature increases with the increase of the charge and converges with the contact time. The gap of temperature between experimental and numerical results is probably due to the parameter of microstructure, where in experimental porosities improve convection in the area, in contrast the numerical materials don't add this phenomena.
Aluminium-water reaction is one of the most promising ways to produce clean and economical hydrogen. In this study, the effect of the waste Aluminium foil AA1235 thickness on Aluminium-water reaction process was investigated. The thickness of aluminum used are 6.5 m, 11.5 m and 19.5 m. Aluminum foil was cut by size 20 mm x 30 mm in each thickness variation. The 0.4 M NaOH and 0.01 M NaAlO 2 was added as promoter on the process. The initial composition of the aluminum and the dislocations in the aluminum are also considered. The experimental results was evaluated by the mass reduction and shrinking core models. The initial composition of the aluminum and the dislocations in the aluminum are also considered. The experimental results were evaluated by the mass reduction and shrinking core models. The results obtained that aluminum with thinner thickness can be approximated by the 1-dimensional slab shrinking core model. Aluminum with a thicker thickness can be approached with a mass reduction model. It is also found out that smaller thickness has larger dislocation and better effects of NaAlO 2 resulting higher yield of hydrogen production.
M-type hexagonal ferrites have wide range of applications in magnetic recording media, microwave devices, micro electrochemical systems, high frequency devices, magneto-optical devices and many more. In present research, M-type strontium hexagonal ferrites doped with ‘magnesium’ having chemical composition (SrMg x Fe 12-x O 19 ) for x= 0.00, 0.05, 00.10, 0.15, 0.20, were synthesized to investigate the influence of rare earth metal doping on the structure and dielectric properties via sol-gel auto combustion technique. Molecular absorption/transmission, structural properties and dielectric response were investigated by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and Dielectric measurements of ‘Mg’ doped strontium hexaferrites. X-ray diffraction analysis verified the magneto-plumbite structure. Crystal sizes were found in varying order for different concentrations of ‘Mg’ ranging from 12.357 to 15.375 nm. The FT-IR spectra exhibited higher frequency band (500–515.84 cm -1 ) indicating tetrahedral site’s vibrations of metallic cations and lower frequency band (385.35–375.16 cm -1 ) exhibiting octahedral sites due to metallic oxygen bond that confirmed the hexagonal structure. The resonance peaks were observed in dielectric constant, loss, tangent loss, AC conductivity, electric modulus and quality factor versus frequency graphs. The dielectric properties were found to be enhanced gradually by increasing concentration of magnesium. The best Q-factor was found for magnesium concentration (x=0.20). The dielectric parameters specify that these ferrite nanoparticles are good applicants for the higher frequency implementations.
The present study deals with the effect of the Diatomite (D) microcomposite with and without chemical modification in a polypropylene (iPP) blend. The objective is to achieve a material with a better performance at a lower cost and more accessible and more suitable processing. The chemical surface modification of Diatomite (MD) was achieved using a crosslinking system based on a mixture of sulfur, accelerator, and peroxide. The iPP/Diatomite composite was prepared by batch melt mixing in a Brabender Plasti-Corde under intense shearing at high temperatures and varying the Diatomite content from 0 to 15 wt%. The rheological behavior was examined by monitoring the Brabender Plasti-Corde torque/time rheographs. Different techniques were used to characterize the sample: Fourier transform infrared spectroscopy (FTIR), WAXS, SEM, and DSC. In addition, tensile strength tests and impact strength mechanical tests were conducted to study the performance. It was found that chemical modification strongly affected rheological behavior and generated a new rheological characteristic compared to the composites without modification. This has induced a new structure form that has improved mechanical properties. Moreover, the chemical modification used and due to its simplicity, can be successfully used on an industrial scale with the appropriate process.
The characteristic pinched hysteresis behavior of memristors has been reported by stacks of a variety of materials. This paper aims to examine the principles of logic design using such two terminal memristive systems for high performance digital circuit applications. As against logic design with standard CMOS, the benefits of logic design with memristors have been stated. The realization and operation of memristor based AND and OR hybrid logic gates obtained by integrating memristors with standard CMOS logic have been discussed. The IMPLY and MAGIC logic families have been demonstrated by covering MAGIC NOR and NAND logic gate implementation with MAGIC NOR in detail. A qualitative comparison has been drawn towards the end of the paper to conclude on the suitability and application space for each of the logic families studied in this paper. This work also describes the hybrid CMOS-memristive logic family known as MRL (Memristor Ratioed Logic). With the addition of CMOS inverters, this logic family's OR and AND logic gates, which are based on memristive components, are given a full logic structure and signal restoration. The MRL family, in contrast to earlier memristor-based logic families, is compatible with conventional CMOS logic.
A material with exceptional levels of abrasion resistance, compressive strength, and hardness is known as bearing steel, also known as EN-31 high-grade carbon alloy steel. It has several uses, including the bulk manufacturing of roller bearings, taps, gauges, ejector pins, swaging dies, etc. The lowest surface roughness (Ra) and highest material removal rate (MRR) are sought for this alloy steel in order for it to be used successfully in a range of applications. In the experiment, a L9 Taguchi orthogonal array design was used to CNC end mill EN-31 steel using a bullnose end mill carbide tool with inserts. This study presents a way for enhancing process factors such as cutting speed, depth of cut, feed rate, and tool corner radius that result in desirable output responses. Taguchi and Taguchi-Grey analyses are used to show the best input values that reduce surface roughness and increase MRR. The lowest level of surface roughness could be attained using the operating parameters of 3000 rpm cutting speed, 500 mm/min feed rate, 0.25 mm depth of cut, and 1.00 mm tool corner radius, while the highest level of material removal rate could be attained using 3000 rpm cutting speed, 2500 mm/min feed rate, 0.25 mm depth of cut, and 1.00 mm tool corner radius.
This investigation inspects the concurrent influence of steel fibers with different materials such as Fly Ash(FA), Silica Fume(SF) and aggregates on the mechanical behaviour of geopolymer concrete (GPC) mixes. A range of 8 to 16 molar NaOH molarities variation was observed in the experimental work. Sodium hydroxide molar (NaOH) and sodium silicate solution (NaOH) were utilised as alkaline activators in proportions of 1, 1.5, and 2 (Na 2 SiO 3 /NaOH). Steel crimped fibers having aspect ratio of 60 were added in the geopolymer concrete. Geopolymer concrete properties considering type of fly ash, the quantity of fly ash, silica fume, the content of fine aggregate and coarse aggregate, effect of sodium hydroxide concentration, content of sodium silicate solution and inclusion of 0.2% of steel fibers in the geopolymer concrete are analyzed.
K2Gd0.97Zr (PO4)3:3mol% Eu3+ were prepared by the solid-state diffusion method and under a vacuum ultra-violet (VUV) region, photoluminescence properties of the phosphor were examined. The phenomenon of visible quantum harvesting via DC was observed in synthesized phosphor for the Gd3+–Eu3+ pair. In the process of quantum harvesting, the two visible light photons are emitted per absorbed VUV photon. This phenomenon occurred upon the 190 nm excitation of Gd3+ at the 6GJ level through a two-step energy transfer from Gd3+ to Eu3+ by cross-relaxation and sequential transfer of the remaining excitation energy. The consequences are that the quantum efficiency of the K2Gd0.97Zr (PO4)3:3mol% Eu3+ phosphor in the energy transfer process from Gd3+ to Eu3+ could reach 233%. The quantum efficiency goes to more than 200% (i.e., 233%) at just low concentration Eu3+ ions (i.e. 3% only). This novelty was found in the prepared phosphor. Therefore, the phosphor K2Gd0.97Zr (PO4)3:3mol% Eu3+ was a potential quantum harvester and potential candidate for mercury free fluorescent lamp and plasma display panel.
This paper reports the synthesis of ZnS Quantum Dots (QDs) embedded in PVA by aqueous precipitation method and its application in antibacterial as well as to find or estimation of Escherichia coli (E.coli) concentration by using ZnS/PVA QD based mem-mode nanodevices. The as-synthesized ZnS/PVA samples are characterized by UV-Vis spectroscopy (UV), Photo luminescence (PL), X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). Antibacterial property of ZnS/PVA QDs against gram positive ( S.aureus ) as well as gram negative (E.coli) are tested. The antibacterial property is found to be more in S.aureus in comparision to E.coli. Mem-behaviour of the as-fabricated devices is observed through electrical characterization. COMSOL MP Software is used for simulating I-V characteristics. The voltage gap is found to be a promising parameter for estimating E.coli concentration with ZnS/PVA QDs as active material and an electrical circuit is presented
Due to outstanding material qualities such as higher strength to weight ratio, resistance to corrosion and resistance to fatigue, titanium alloys (Ti-6Al-4V) are widely applied in aerospace industries. Such a challenging to machine and necessary expensive convenctional machinery materials can cut using Electrical Discharge Machining (EDM). This work involves the study of influence of process characteristics on the performance quality of EDM during machining of Ti-6Al-4V. The process characteristics that are considered in this study are Current (9-15amps) or Input power (I.P. of 3-5 kVA), pulse on (60-80 μsec) and pulse off (20-40μsec) times, the pressure of dielectric fluid (6-10 MPa). The effectiveness of the EDM is measured using rate of tool wear (TWR) and rate of material removal (MRR) during machining, taper angle and surface roughness (SR). Dry brass multi hole tool electrode is used along with deionized water as the dielectric medium. Taguchi L18 orthogonal design is used for experimentation. The optimal combination of process characteristics is determined.
Road markings regulate and direct traffic by conveying specific information. It is of great significance to develop new road marking materials and improve the visibility of marking materials for improving traffic efficiency and ensuring traffic safety. This paper summarized the development status of various reflective road markings at home and abroad. In addition, the energy storage luminescent fluorescent/phosphor marking lines in road marking was emphatically generalized to evaluate the advantages and disadvantages of different improvement methods. Overall, strontium aluminate doped with Eu 2+ co-doped with Dy 3+ (SrAl 2 O 4 :Eu 2+ , Dy 3+ ) phosphors and self-luminous pavement for energy storage had great prospects in improving road safety and reducing energy consumption.
In the present research work, carbon nanosphere (5 wt. %, 10 wt. % and 15 wt. %)/Zr- based metal organic frame works (CNS: Zr (II)-MOFs) with different molar ratios of the legend 4-{[(1 E )-1-Hydroxy-3-Oxoprop-1-En-2-yl] Sulfanyl} Benzoic Acid (HOSBA) have been successfully synthesized by hydrothermal method. Studies using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) have validated certain structural, optical, and morphological features. The supercapacitance performance of the synthesized MOFs was investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). At a current density of 0.5 A g -1 and at a scan rate of 10 mV/s, the 15% CNS doped Zr-MOF demonstrated highest specific capacitance (C s ) of 239.4 F g -1 . 15 wt.% CNS doped Zr-MOF proven power density of 2100 W kg -1 and maximum energy density of 14.82 Wh Kg -1 with capacitive retention of 77.63 % following 2000 cycles mark this combination a good for supercapacitors (SCs) material. Regardless of the synthetic conditions, we achieved MOFs which exhibited hetero structure formation with spherical morphologies. The results open us new and energy approach for the supercapacitor of the Zr-metal based MOFs and applications in the photonics, optoelectronics, and promising electrode material for electrochemical energy storage systems.
The key drivers of the growing interest in the recovery of local materials, particularly land and waste plants, are low-cost building materials, thermal comfort, decreased energy consumption, and decreased carbon dioxide polluting emissions. This work's primary objective is to test a bio-sourced composite material that takes the form of a block of unfinished soil that has been stabilized with cement and blended with wheat straw. This study is being done with the objective of examining the impact of this fiber at different weight percentages (0, 2, 3%, and 4%) on the mechanical behavior, durability, and thermophysical properties of the produced blocks. The results obtained indicated an increase in thermal conductivity, from 2.75 W/mK for the blocks without wheat straw fiber to 0.398 W/mK for those getting 4% of the wheat straw fiber, signifying an improvement in thermal insulation. While retaining the low performance threshold required by the earth construction standard, this improvement was accompanied by an average decrease in mechanical performance.
Friction stir welding is now increasingly being applied to joining aluminum alloys and other non-ferrous metals because the process has been established to be more suitable for joining soft metals. Compared with the facilities required for fusion welding, procuring friction stir welding machine is capital intensive and its utilization in the underdeveloped nations is very scanty. In this work, some experimental works were done so as determine the optimized process parameters for friction stir welding of aluminium alloys using an adapted vertical milling machine. The focus is to optimize the friction stir welding of AA1100 using an adapted vertical milling machine so as to obtain high quality weldments in terms of hardness and tensile strength. Friction stir welding of AA1100 was performed within a process window. The process parameters were optimized for improved hardness and tensile strength. The hardness property of the welded joints was measured using Brinnel hardness tester while the tensile strength was measured using Instron universal testing machine. Within the range of parameters utilized in this work, the hardness and tensile strength of the friction stir welded joint of AA1100 ranged between 15.30—35.32 BHN and 48.66 – 99.12 MPa respectively. The highest hardness value of 35.32 BHN was found at optimum parametric setting of 900 rpm rotational speed, 40 mm/min traverse speed and 2 o tilt angle while the highest tensile strength of 99.12 MPa was obtained at optimal processing parameters of 900 rpm rotational speed, 25 mm/min traverse speed and 2 o tilt angle. The ANOVA revealed that rotational speed followed by tilt angle has the most significant effect on the tensile strength of the weldment. The tilt angle and the traverse speed effects were found significant on the hardness of the weldments.
Analytical expressions are obtained for the wave functions and the energy spectrum of charge carriers in the β-HgS nanolayer of a cylindrical core/shell/shell β-CdS/ β-HgS/ β-CdS nanocomposite in the presence of a strong lateral uniform electrostatic field. It is shown that, under the influence of an external field, the position of the chemical potential of the electron-hole subsystem at absolute zero shifts to the bottom of the conduction band of the sample. The displacement value is determined by the intensity of the external field and increases linearly with increasing field. The concentration, internal energy, and heat capacity of the electronic subsystem of the β-HgS layer in the presence of a field are compared with similar values in the absence of a field. Calculations show that under identical conditions, the presence of an external field leads to an increase in the carrier concentration, which in turn leads to an increase in the internal energy and heat capacity of the system of electrons and holes in the layer.
