Spaceborne and airborne sensors in water quality assessment

Remotely sensed data can increase the ability of water resources researchers and decision-makers to monitor waterbodies more effectively. In recent decades, remote-sensing techniques have been widely used to measure the qualitative parameters of waterbodies (i.e. suspended sediments, coloured dissolved organic matter (CDOM), chlorophyll-a, and pollutants). A large number of different sensors on board various satellites and other platforms, such as aeroplanes, are currently used to measure the amount of radiation at various wavelengths reflected from the water’s surface. In this review article, the more commonly employed spaceborne and airborne sensors used in water quality investigations are introduced and their utility in the quantitative assessment of the quality parameters of waterbodies is discussed. Various properties (spectral, spatial and temporal, etc.) of spaceborne and airborne sensors are tabulated to be used as a sensor selection guide. These tables are helpful when designing water quality assessment studies, and can be used for the selection of appropriate sensors among many other available sensors in the market. Finally, based on the literature survey, a compilation of sensors used to measure various water quality parameters is presented.     

Wireless Node Localization under Hostile Radio Environment using Smart Antenna

This paper presents a resilient localization scheme for wireless sensor networks (WSNs). It suits well in estimation of node position under a corrupted radio environment. Position computation is based on information of angle-of-arrivals (AoA) and references obtained from a few mobile anchors. In the network, anchors are equipped with smart antennas and global positioning system receivers. They broadcast signals in a synchronous and periodic fashion. The neighboring nodes having the signals with received signal strength values above a prescribed threshold level, respond with their respective IDs. Anchors evaluate AoA information from these signals using estimation of signal parameters via rotational invariance technique (ESPRIT) algorithm. Next, they forward beacon messages, containing their references and estimated angles, to the corresponding nodes and move along random trajectories. After receiving three sets of such data, at least, nodes can initiate selective segregation of the inconsistent position estimations. Simulation results attaining higher degree of localization accuracy validate its competency over the existing schemes.

     

Multiparty Quantum Key Agreement With Strong Fairness Property

Multiparty Key Agreement (MKA) is the backbone for secure multiparty communication. Although numerous efficient MKA-cryptosystems are available in the classical field, their security relies on the assumption that some computational issues are infeasible. To overcome this dependency, a new area, quantum cryptography, evolves to support key agreement among two or more participants securely. In this paper, first, we present a two-part quantum key agreement with Strong Fairness Property (SFP) and extends it to a Multiparty Quantum Key Agreement (MQKA) protocol. In the first round of proposed MQKA, a participant will act as a group controller (GC) and establishes two-party groups with each of the residual participants and agreed on a quantum two-party-style shared key per each of the two-party. In the second round, the GC computes public keys for each of the respective parties by combining these two-party keys using XOR-operation, excluding that party’s two-party key. Next, the GC sends separate public keys to the individual participants. After receiving the respective public-key, each of the respective participants computes the multiparty key by joining their public-key with their two-party key using XOR. Finally, GC computes the multiparty key, as the GC knows all the two-party keys, it combines them with XOR and acts as a usual group participant. The proposed protocol has compared with other renowned MQKA protocols in terms of four standards parameters, namely transmission number (TN), qubit measurement number (QM), qubit for channel checking (QCC), and the qubit efficiency (QE) and acceptable results achieved. The security of the proposed MQKA relies on the absolute security of a two-part quantum key agreement with Strong Fairness Property (SFP). Moreover, it is secure against both internal and external attacks.     

Dynamic-Compiler-Driven Control for Microprocessor Energy and Performance

A general dynamic-compilation environment offers power and performance control opportunities for microprocessors. The authors propose a dynamic-compiler-driven runtime voltage and frequency optimizer. A prototype of their design, implemented and deployed in a real system, achieves energy savings of up to 70 percent.     

Emission from utilization of producer gas and mixes of jatropha biodiesel

This paper reports about the discharge characteristics of jatropha biodiesel blends along with producer gas from waste babul wood pieces in a dual-fuel direct injection diesel engine. The biodiesel blends were examined in both individual and dual-fuel modes at a constant gas flow rate of 21.69 kg/h at all loading conditions. From the results it may be concluded that oxides of nitrogen and smoke opacity reduce, whereas carbon dioxide (CO₂), carbon monoxide (CO), and hydrocarbon (HC) increase for all test fuels in dual-fuel operation compared with that of a single style at different loading conditions. The fuel blends show better emissions than that of diesel in both the ways.     

DYPLAS, a finite element dynamic elastic-plastic large deformation analysis program

DYPLAS is a computer program designed to compute the response history of general three-dimensional structures subjected to transient thermal and mechanical loadings. The analysis considers nonlinearities arising from material behavior as well as from large deformations that may occur in the structure. Elastic-plastic behavior with isotropic hardening is included by means of incremental relations of the Prandtl-Reuss type combined with a variant of the ‘plastic strain-total strain’ method. Reduction of the constitutive relations to the case of generalized plane stress is also presented. Spatial discretization is achieved by applying the displacement formulation of the finite element method. In order to achieve reasonable computational time, the number of computational points used in the algorithm for numerical integration over the volume of each finite element required minimization; a triangular, flat-plate bending element is cited as an example for which this minimization was achieved satisfactorily. An explicit scheme is used for computation of dynamic response. With this scheme, formation of a global stiffness matrix is not needed. Consequently, the usual limitations arising from bandwidth or problem size are completely eliminated.     

Role of dopants in Bi-Sr-Ca-Cu-O system

The role of Al and Ag dopants in the nominal composition, 4336 of Bi-Sr-Ca-Cu oxide has been studied, using a new chemical phase analysis method known as differential dissolution besides XRD and resistivity and magnetic susceptibility measurements. Our investigation reveals that (a) it is relatively easy to realize high-T _c phase (2223) in both Al- and Ag-doped samples with the same nominal composition and heat treatment history (b) both samples consist of superconducting phases with more or less the same basic composition and equal amounts, (c) 2112 phase may be a superconductor and (d) superconducting properties with Al and Ag dopants are different.     

Radio wave propagation through rain forests of India

A radio wave attenuation measurement survey program was undertaken for the tropical rain forests of India. Measurements were taken at frequencies from 50 to 800 MHz, for antenna heights from 1.5 to 16.5 m above the ground with both horizontally and vertically polarized emissions, and at various separation distances varying from 40 to 4000 m. There were 96 combinations of system parameters for each selected distance between transmitting and receiving locations. In addition to the copolar measurements, cross-polar measurements were carried out to study cross-polar phenomenon in the presence of vegetation. The results of the studies are discussed, covering scatter of the data, lack of homogeneity of the foliage, variation in foliage proximity of the antenna, scattering of radio waves, effect of antenna beamwidth, effect of changes in wind velocity, frequency and polarization dependence of the basic transmission loss, seasonal variation of the loss, effect of climate and type of vegetation, foliage loss, specific attenuation, and effect of increased antenna height in the forest. An empirical model derived from these measurements is proposed     

A Technique of Modulating Pulsed Semiconductor Lasers

This paper gives details of the pulse-position modulation technique as applied in the case of a pulsed room-temperature-operated GaAs laser diode for communication purposes. The input analog signal is converted into a digital format and information transmission takes place through the laser pulses occurring at different positions in time. Special care is taken to synchronize the receiver with the transmitter. At the receiver the analog information is reconstructed. The technique can be incorporated in the development of a short-haul point-point-to-point voice communication system using the laser diode.     

Shift of millimeterwave window frequencies in relation to tropospheric radio meteorological parameters

In view of wide application areas of the millimeterwave frequency band (18–300 GHz) in recent years for various civil and defence applications including radar and communications, remote sensing and radio astronomy, we were prompted to undertake a theoretical estimate of the variation of specific attenuation (dB/Km) with radio meteorological parameters in clear weather conditions. The results of the estimation of the attenuation in this frequency band for some major locations in India from available radio meteorological data from NOAA, USA are presented in this paper. An appreciable amount of shift, which is mainly a function of the atmospheric pressure, temperature and relative humidity was noticeable in each of the window frequencies around 35, 94, 140 GHz and 220 GHz.