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Feasibility analysis of WdM links for radar applications

defence Technology（防务技术） 2015年第1期11卷 76-84页

作者： d.meena FREdY FRANCIS K.T.SARATH E.dIPIN T.SRINIVAS Applied Photonics Lab ECE Department Indian Institute of Science(IISc) Electronics and Radar development Establishment (LRdE) DRDO(Ministry of Defence) Bangalore India Model Engineering College Thrikkakara Cochin India

Active phased array antennas enhances the performance of modern radars by using multiple low power transmit/receive modules in place of a high power transmitter in conventional radars. Fully distributed phased array radars demand the distribution of various signals in radio frequency(RF) and digital domain for real time operation. This is normally achieved through complex and bulky coaxial distribution networks. In this work, we intend to tap the inherent advantages of fiber links with wavelength division multiplexed(WdM) technology and a feasibility study to adapt these links for radar applications is carried out. This is done by analysing various parameters like amplitude, delay, frequency and phase variation response of various radar waveforms over WdM links. This also includes performance evaluation of non-linear frequency modulation(NLFM) signals, known for better signal to noise ratio(SNR) to specific side lobe levels. NLFM waveforms are further analysed using pulse compression(PC) technique. Link evaluation is also carried out using a standard simulation environment and is then experimentally verified with other waveforms like RF continuous wave(CW), pulsed RF and digital signals. Synchronization signals are generated from this variable duty cycle digital signals during real time radar operation. during evaluation of digital signals, variable transient effects for different duty cycles are observed from an amplifier configuration. A suppression method is proposed to eliminate this transient effects. Further, the link delay response is investigated using different lengths of fiber spools. It can be inferred from the experimental results that WdM links are capable of handling various signals significant to radar applications.

关键词： WdM Radar RF over fiber EdFA transient delay CW Pulsed CW NLFM

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Influence of cerium ions on structure-dependent magnetic properties of Ba-Sr M-type hexaferrite nanocrystals

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Journal of Rare Earths 2024年第2期42卷 364-372,I0005页

作者： Ram A.Pawar Sunil M.Patange P.M.dighe Sher Singh meena Abdullah GAl-Sehemi Mehboobali Pannipara Santosh S.Jadhav department of Physics ArtsCommerce and Science CollegeAhmednagar413711MaharashtraIndia department of Physics Shri Krishna MahavidyalayaGunjotiDistOsmanabad413606MaharashtraIndia Padmashri Vikhe Patil College of Arts Science and CommercePravaranagarA/P.Loni(Kd)Tal.RahataDistAhmednagar413713MaharashtraIndia Solid State Physics division Bhabha Atomic Research CentreMumbai400085MaharashtraIndia department of Chemistry King Khalid UniversityAbha61413Saudi Arabia department of Physics D.S.M's ArtsCommerce and Science CollegeJintur431509MaharashtraIndia

The present study is a systematic effort to investigate the structure-sensitive magnetic parameters of Ce^(3+) substituted Ba-Sr hexaferrite nanocrystals chemically formulated as Ba_(0.5)Sr_(0.5)Ce_(x)Fe_(12-x)O_(19) where x=0.0-0.2 with Δx=*** hexaferrite powders were prepared using the sol-gel self-ignition route and structurally characterized by means of powder X-ray diffraction and Fourier transform infrared *** creation of the M-type hexaferrite phase within the synthesized samples was revealed from the Rietveld refinement of the X-ray *** occurrence of a secondary phase of CeO_(2) was revealed within the hexaferrites for the substitution,x> *** refined X-ray diffraction data were utilized to compute the lattice parameters,X-ray density,and lattice parameter *** crystal structure plotted from the refined XRd data reveals the occupancy of the ions at different lattice *** XPS data of the hexaferrite were analyzed to confirm the oxidation states of the constituent *** nanocrystalline nature of the hexaferrites was revealed from the crystallite sizes calculated using Scherer's *** analysis of FTIR spectra confirms that only a fraction of Ce^(3+)accommodated in the lattice and the remaining Ce content reside in the form of the CeO_(2) *** morphology of the hexaferrites was analyzed from the FESEM profiles of the ferrite *** magnetic behavior study was performed by analyzing the Curie temperature,hysteresis loops,and hyperfine interactions by means of susceptibility,V.S.M,and Mossbauer spectroscopy,*** hexaferrites with increasing coercivity,decreasing saturation magnetization,and decreasing Curie temperature are reported in the *** substituted Ce^(3+)ions inhibit the grain growth and create lattice imperfections giving rise to hexaferrites with tuned magnetic parameters suitable for different applications.

关键词： Ba-Sr hexaferrite Ce^(3+)substitution XPS Saturation magnetization Coercivity M?ssbauer spectroscopy

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Effect of calcium lactate on compressive strength and self-healing of cracks in microbial concrete

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Frontiers of Structural and Civil Engineering 2019年第3期13卷 515-525页

作者： Kunamineni VIJAY meena MURMU department of Civil Engineering National Institute of TechnologyRaipur 492010India

This paper presents the effect on compressive strength and self-healing capability of bacterial concrete with the addition of calcium *** to normal concrete,bacterial concrete possesses higher durability and engineering concrete *** production of calcium carbonate in bacterial concrete is limited to the calcium content in *** calcium lactate is externally added to be an additional source of calcium in the *** influence of this addition on compressive strength,self-healing capability of cracks is highlighted in this *** bacterium used in the study is bacillus subtilis and was added to both spore powder form and culture form to the *** subtilis spore powder of 2 million cfu/g concentration with 0.5%cement was mixed to *** lactates with concentrations of 0.5%,1.0%,1.5%,2.0%,and 2.5%of cement,was added to the concrete mixes to test the effect on properties of *** other samples,cultured bacillus subtilis with a concentration of 1×10^cells/mL was mixed with concrete,to study the effect of bacteria in the cultured form on the properties of *** of 100 mm×100 mm×100 mm were used for the *** cubes were tested after a curing period of 7,14,and 28 d.A maximum of 12%increase in compressive strength was observed with the addition of 0.5%of calcium lactate in *** electron microscope and energy dispersive X-ray spectroscopy examination showed the formation of ettringite in pores;calcium silicate hydrates and calcite which made the concrete denser.A statistical technique was applied to analyze the experimental data of the compressive strengths of cementations *** surface methodology was adopted for optimizing the experimental *** regression equation was yielded by the application of response surface methodology relating response variables to input *** method aids in predicting the experimental results accurately with an acceptable range

关键词： calcium lactate bacillus subtilis compressive strength self-healing of cracks

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Mitigation of EdFA transient effects in variable duty cycle pulsed signals

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defence Technology（防务技术） 2019年第3期15卷 276-281页

作者： d. meena K.T. Sarath Fredy Francis E. dipin T. Srinivas Electronics and Radar development Establishment (LRdE) DRDO Bangalore Karnataka 560093 India Model Engineering College Thrikkakara Cochin Kerala 682021 India Indian Institute of Technology Madras Chennai Tamil Nadu 600036 India

We report the transient effects in Erbium doped Fiber Amplifier (EdFA) systems for pulsed signals with different duty-cycles. The work includes the analysis using three different duty-cycles, 10%, 20% and 50%. A curve fitting technique is also proposed to predict the transients of any lesser duty-cycled pulse, once the transients of a larger duty-cycled pulse is known. Mathematical evaluation confirms the double exponential shape of transient distorted signal. Further, EdFA transient effect is experimentally verified on a Wavelength division Multiplexed (WdM) link by multiplexing high and low bitrate modulated optical signals. We conclude the paper by proposing a transient suppression technique for variable dutycycle signals and analyzing its effectiveness with different wavelength spacing.

关键词： EdFA Transients WdM Variable duty cycle Suppression

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Geodesic γ-Pre-E-Convex Functions on Riemannian Manifolds

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Journal of Mathematical Research with Applications 2023年第3期43卷 324-334页

作者： Seema meena d.B.OJHA department of Mathematics Faculty of Science University of Rajasthan

In this paper, we generalize geodesic E-convex function and define geodesic γ-pre-E-convex and geodesic γ-E-convex functions on Riemannian manifolds. The sufficient condition of equivalence class of geodesic γ-pre-E-convexity and geodesic γ-E-convexity for differentiable function on Riemannian manifolds is studied. We discuss the sufficient condition for E-epigraph to be geodesic E-convex set. At the end, we establish some optimality results with the aid of geodesic γ-pre-E-convex and geodesic γ-E-convex functions and discuss the mean value inequality for geodesic γ-pre-E-convex function.

关键词： geodesic E-convex set geodesic γ-pre-E-convex function geodesic γ-E-convex function optimality conditions

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TMTACS: Two-Tier Multi-Trust-Based Algorithm to Countermeasure the Sybil Attacks

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Computers, Materials & Continua 2022年第11期73卷 3497-3512页

作者： meena Bharti Shaveta Rani Paramjeet Singh department of Computer Science and Engineering I.K.Gujral Punjab Technical UniversityKapurthala144603PunjabIndia department of Computer Science and Engineering Maharaja Ranjit Singh Punjab Technical UniversityBathinda151001PunjabIndia

Mobile Ad hoc Networks(MANETs)have always been vulnerable to Sybil attacks in which users create fake nodes to trick the system into thinking they’re *** fake nodes need to be detected and deactivated for security reasons,to avoid harming the data collected by various *** MANET is an emerging field that promotes trust management among *** is becoming more essential in the communication process,which is why clear and honest communication strategies are *** Management allows for MANET devices with different security protocols to *** a device finds difficulty in sending a message to the destination,the purpose of the communication process won’t be achieved and this would disappoint both that device and all of your devices in *** paper presents,the Two-Tier Multi-Trust based Algorithm for Preventing Sybil Attacks in MANETs(TMTACS).The TMTACS provides a two-tier security mechanism that can grant or revoke trust in the Nodes of the ***’s a smart way to identify Sybil nodes in the system.A proficient cluster head selection algorithm is also defined,which selects cluster head efficiently and does load balancing to avoid resource consumption from a single node ***,for routing efficient path is selected to deteriorate energy consumption and maximize *** recent technique is compared with Secured QoS aware Energy Efficient Routing(SQEER),Adaptive Trust-Based Routing Protocol(ATRP),and Secure Trust-Aware Energy-Efficient Adaptive Routing(STEAR)in terms of Packet delivery Ratio(PdR),consumption of energy *** simulation was performed on MATrix LABoratory(MATLAB)and the results achieved by the present scheme are better than existing techniques.

关键词： Malicious node sybil attack MANET trust management security

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Revolutionizing Thermal Stability and Self‑Healing in Pressure Sensors:A Novel Approach

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Advanced Fiber Materials 2023年第6期5卷 2028-2039页

作者： Su Bin Choi Jagan Singh meena Jong‑Woong Kim department of Smart Fab Technology Sungkyunkwan UniversitySuwon 16419Republic of Korea Research Center for Advanced Materials Technology Core Research InstituteSungkyunkwan UniversitySuwon 16419Republic of Korea School of Mechanical Engineering Sungkyunkwan UniversitySuwon 16419Republic of Korea

Soft electronics,which require mechanical elasticity,rely on elastic materials that have both a small Young’s modulus and a large elastic strain *** materials,however,are prone to damage when stress accumulates,presenting a significant challenge for soft *** address this issue,the integration of self-healing functionality into these materials appears to be a promising *** covalent bond chemistry has been utilized to design high-strength polymers with controllable ***,the temperature needed to trigger self-healing may induce thermal damage to other parts of the *** contrast,if the self-healing temperature is reduced,the device might suffer damage when exposed to temperatures exceeding the self-healing point due to the low stability of the polymer at high *** challenges highlight the need for materials that can self-heal at low temperatures while maintaining thermal stability at high *** response to this challenge,we propose a novel approach that involves forming a microfibrous network using polycaprolactone(PCL),a material with a low melting temperature of 60°C that is widely utilized in shape memory and self-healing *** fabricated the conductive fiber by encapsulating a microfiber PCL network with MXene *** MXene nanosheets were seamlessly coated on the PCL fiber’s surface to prevent shape deformation at high ***,they exhibited high thermal conductivity,facilitating rapid internal heat ***,the MXene/PCL microfiber networks demonstrated self-healing capabilities at 60°C and thermal stability above 200°*** makes them potentially suitable for stretchable,self-healing electronic devices that need to withstand high temperatures.

关键词： Fibers MXene Self-healing Pressure sensor Thermal stability Electrospinning

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Application of response surface methodology(RSM) for optimization of leaching parameters for ash reduction from low-grade coal

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International Journal of Mining Science and Technology 2018年第4期28卷 617-625页

作者： Sushanta Kumar Behera Himanshu meena Sudipto Chakraborty B.C.Meikap department of Chemical Engineering Indian Institute of Technology (IIT) Kharagpur department of Chemical Engineering School of Engineering Howard College University of Kwazulu-Natal (UKZN)

Coal is the world＇s most abundant energy source because of its abundance and relatively low cost. due to the scarcity in the supply of high-grade coal, it is necessary to use low-.grade coal for fulfilling energy demands of modern civilization. However, due to ItS high ash and moisture content, low-grade coal exerts the substantial impact on their consumption like pyrolysis, liquefaction, gasification and combus- tion process. The present research aimed to develop the efficient technique for the production of clean coal by optimizing the operating parameters with the help of response surface methodology. The effect of three independent variables such as hydrofluoric acid （HF） concentration （10-20% by vo!ume ）,. temper- ature （60-100 ~C）, and time （90-180 min）, for ash reduction from the low-grade coal was Investigated.. A quadratic model was proposed to correlate the independent variables for maximum ash reduction at the optimum process condition by using central composite design （CC.d）method. The study reveals that HF concentration was the most effective parameter for ash reduction in comparison with time and temper- ature. It may be due to the higher F-statistics value for HF concentration, which effects to large extent of ash reduction. The characterization of coal was evaluated by Fourier transform infrared spectroscopy （FTIR） analysis and Field-emission scanning electron microscopy with energy-dispersive X-ray （FESEM- EdX） analysis for confirmation of the ash reduction.

关键词： Low-grade coal Hydrofluoric acid (HF)Leaching Ash reduction Response surface methodology

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Higher-Order (F,α,β,ρ,d,E)-Convexity in Fractional Programming

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Journal of Mathematical Research with Applications 2023年第3期43卷 303-312页

作者： Himanshu TIWARI Seema meena deepak KUMAR d.B.OJHA department of Mathematics Faculty of Science University of Rajasthan

In this paper we define higher order (F,α,β,ρ,d,E)-convex function with respect to E-differentiable function K and obtain optimality conditions for nonlinear programming problem (NP) from the concept of higher order (F,α,β,ρ,d)-convexity. Here, we establish Mond-Weir and Wolfe duality for (NP) and utilize these duality in nonlinear fractional programming problem.

关键词： E-convexity higher order (F,α, β, ρ, d,E)-convexity optimality conditions duality fractional programming

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Long-Term Effects of different Passages of Vehicular Traffic on Soil Properties and Carbon Storage of a Crosby Silt Loam in USA

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Pedosphere 2019年第2期29卷 150-160页

作者： Gulab Singh YAdAV Rattan LAL Ram Swaroop meena Basant RIMAL Carbon Management and Sequestration Centre the Ohio State University

The passage of vehicles with heavy axle loads causes soil compaction, and this adversely affects soil properties and crop *** adverse effects can persist for several years due to significant changes in key soil properties. However, the mechanisms of the aforementioned effects are not well understood for conservation agriculture(CA)(e.g., no-till(NT)) wherein the use of heavy machinery is considerably common. Therefore, known compaction forces(0 Mg load for compaction(NT-0, control), two passages of 2.5 Mg water wagon axle load(NT-2), and four passages of 2.5 Mg water wagon axle load(NT-4)) were applied to all the plots annually for 20 consecutive years. The experiment was established in 1997 at the Waterman Agricultural and Natural Resources Laboratory(WANRL), Ohio State University, Columbus, Ohio. Each treatment was replicated thrice. Soil samples were obtained in November2016 to determine the effects of variations in the axle load and vehicular passages on carbon(C) and nitrogen(N) storage and selected soil properties of a Crosby silt loam soil under NT-based corn-soybean rotation with residue retention in Central Ohio, USA. Three locations were also randomly selected in an adjoining natural woodlot(WL) soil plot and sampled(30 m away from the compaction field) to compare the effects of vehicular traffic on soil under NT with WL soil. Results revealed that soil bulk density(ρb) and total porosity at 0–10 and 10–20 cm depths were not affected by the passages of vehicular traffic for 20 years under the NT *** penetration resistance(PR)(1.86 and 2.03 MPa at 0–10 and 10–20 cm soil depths, respectively) was significantly higher under NT-4 compared with that under other treatments. Saturated hydraulic conductivity at 0–10 and 10–20 cm soil depths ranged from19.7 to 31.4 and 18.5 to 29.5 mm d^(-1), respectively, across all the treatments. The proportion of macroaggregates(> 0.25 mm) and microaggregates(diameter and geometric mean diam

关键词： carbon stock heavy machinery no-till residue retention soil aggregates soil compaction soil quality well-drained soil

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