Generalized M-2M Mapping Scheme for SLM and PTS Based OFDM Systems Without Side-Information

Orthogonal frequency division multiplexing (OFDM) is an attractive multicarrier modulation scheme, but it suffers from the problem of high peak-to-average power ratio (PAPR). Selected mapping (SLM) and partial transmit sequences (PTS) are two well known, distortion-less techniques with good PAPR reduction capabilities. But, both the methods require side information (SI) about the phase rotation factors to recover the original data signal at the receiving end. The transmission of SI not only results in data rate loss but also, in BER performance degradation if SI gets corrupted over the channel. In this paper we have proposed a new mapping scheme, named “ $M\text{- }2M$ Mapping scheme” for SLM and PTS based methods to completely eliminate the requirement of SI at the receiver. In this scheme $M$ data points are mapped to the constellation points of 2M-ary modulation scheme using (1, j) as the phase rotation factors. Some criteria are suggested with which the method is applied for different constellation sizes, $M=4$ to $M=16$ . The method can be easily coupled with conventional SLM and PTS techniques. When compared with the existing methods like multi point square mapping, which do not need SI, our technique is scalable and provides good PAPR reduction capability with consistent BER performance.     

Analysis of L-probe Proximity Fed Annular Ring Patch Antenna for Wireless Applications

In the present paper, annular ring patch antenna with L-probe feeding has been analyzed using modal expansion cavity model. The proposed antenna shows wide band and ultra wide band operation which depends on the position of L-probe feeding and position of the shorting pin. For the fundamental \(\hbox {TM}_{11}\) mode, the bandwidth and gain is found to be 38.85 % and 7.8 dBi while for higher order \(\hbox {TM}_{12}\) mode bandwidth is obtained 58.71 % with corresponding gain of 6.1 dBi. The effect of shorting pin on the proposed antenna is also studied and it is found that the radiating structure is more compact in nature and improves the bandwidth upto 47.37 % with 8.0 dBi gain. Further, the proposed antenna has broadside radiation pattern over the entire bandwidth. The theoretical results are compared with IE3D simulated results which are in good agreement.     

Daylight integrated illumination control of LED systems based on enhanced presence sensing

Light emitting diodes (LEDs) are considered to become the dominant source of illumination in the future, offering long life times, energy efficiency and flexible tunability. The flexibility of adapting LED parameters offers multiple degrees of freedom in designing LED based lighting systems. In this paper, we consider energy-efficient illumination control design of LED based lighting systems in office spaces. Our goal is to determine the optimum dimming levels of the LED sources so as to minimize the power consumption while rendering (i) uniform illumination at a given illumination level in workspace regions that are occupied, and (ii) a minimum illumination level of lower value in unoccupied regions, while taking daylight distribution over the workspace plane into account. In order to determine occupant locations, we present an ultrasound array sensor solution with enhanced presence detection capability. We further propose a method to estimate and disaggregate illumination contributions of daylight and the different LED sources at the workspace plane. The performance of our proposed control solution is evaluated under different occupancy scenarios.     

Semi-automated detection of trace explosives in fingerprints on strongly interfering surfaces with Raman chemical imaging

We have previously demonstrated the use of wide-field Raman chemical imaging (RCI) to detect and identify the presence of trace explosives in contaminated fingerprints. In this current work we demonstrate the detection of trace explosives in contaminated fingerprints on strongly Raman scattering surfaces such as plastics and painted metals using an automated background subtraction routine. We demonstrate the use of partial least squares subtraction to minimize the interfering surface spectral signatures, allowing the detection and identification of explosive materials in the corrected Raman images. The resulting analyses are then visually superimposed on the corresponding bright field images to physically locate traces of explosives. Additionally, we attempt to address the question of whether a complete RCI of a fingerprint is required for trace explosive detection or whether a simple non-imaging Raman spectrum is sufficient. This investigation further demonstrates the ability to nondestructively identify explosives on fingerprints present on commonly found surfaces such that the fingerprint remains intact for further biometric analysis.     

A Simple Approach to the Determination of Threshold Stress Intensity for Stress Corrosion Cracking (K ISCC) and Crack Growth of Sensitized Austenitic Stainless Steel

This article discusses the intricacies associated with the determination of threshold stress intensity for stress corrosion cracking (K _ISCC) of narrow regions such as the sensitized microstructure of austenitic stainless steel and presents a simple approach to the accurate determination of K _ISCC of a sensitized stainless steel. K _ISCC and crack growth rates of solution-annealed and sensitized AISI 304 stainless steel in the 42 wt pct MgCl₂ environment at 427 K (154 °C) were determined using the circumferential notch tensile (CNT) technique. The results presented here validate the ability of the CNT technique to overcome some of the fundamental difficulties in determination of the K _ISCC of narrow regions, using the traditional techniques. This article also discusses the mechanistic aspects of the difference in fractographic features of the sensitized and solution-annealed stainless steels.     

Room-temperature magnetic studies of La-modified BiFeO3 ceramic

Magnetic studies of La-modified BiFeO₃ ceramic with x = 0.0, 0.20 and 0.25 synthesized by solution combustion method are reported. X-ray diffraction, Differential scanning calorimetry and Vibrating sample magnetometer are used to characterize the powder samples. La substitution for Bi in BiFeO₃ ceramic increased the Room-temperature saturation magnetization (M_s) and remanent magnetization (M_r). Mössbauer spectroscopy confirmed the presence of single-phase material for the doped compositions. A significant enhancement of antiferromagnetic Neel temperature T_N and saturation magnetization M_s for x = 0.25 sample is observed as compared to BiFeO₃.     

Uncertainty quantification in nanomechanical measurements using the atomic force microscope

Quantifying uncertainty in measured properties of nanomaterials is a prerequisite for the manufacture of reliable nanoengineered materials and products. Yet, rigorous uncertainty quantification (UQ) is rarely applied for material property measurements with the atomic force microscope (AFM), a widely used instrument that can measure properties at nanometer scale resolution of both inorganic and biological surfaces and nanomaterials. We present a framework to ascribe uncertainty to local nanomechanical properties of any nanoparticle or surface measured with the AFM by taking into account the main uncertainty sources inherent in such measurements. We demonstrate the framework by quantifying uncertainty in AFM-based measurements of the transverse elastic modulus of cellulose nanocrystals (CNCs), an abundant, plant-derived nanomaterial whose mechanical properties are comparable to Kevlar fibers. For a single, isolated CNC the transverse elastic modulus was found to have a mean of 8.1?GPa and a 95% confidence interval of 2.7-20?GPa. A key result is that multiple replicates of force-distance curves do not sample the important sources of uncertainty, which are systematic in nature. The dominant source of uncertainty is the nondimensional photodiode sensitivity calibration rather than the cantilever stiffness or Z-piezo calibrations. The results underscore the great need for, and open a path towards, quantifying and minimizing uncertainty in AFM-based material property measurements of nanoparticles, nanostructured surfaces, thin films, polymers and biomaterials.     

Isobutrin from butea monosperma (flame of the forest): a promising new natural sensitizer belonging to chalcone class

In this work, "isobutrin", an ecofriendly sensitizer that is extracted from Butea monosperma (commonly known as "Flame of the Forest") flowers, is introduced. It is a bright yellow pigment belonging to the chalcone class and is examined as a sensitizer for optoelectronic applications. It is observed that chelation of this dye with Ti ions results into a strong dye-TiO(2) charge transfer (DTCT) band in the visible region. This Ti-Isobutrin chelate is stable, irreversible and its formation is studied using Benesi-Hildebrand plot. The locations of HOMO-LUMO states of the Ti-isobutrin chelate and the corresponding band alignment with TiO(2) are obtained. Also, a thermal stability test revealed that isobutrin is stable above 100 °C.