Muhammad Arshad Kamran

Single-Step Synthesis of Monolithic Comb-like CdS Nanostructures with Tunable Waveguide Properties

Using a simple in situ seeding chemical vapor deposition (CVD) process, comb-like (branched) monolithic CdS micro/nanostructures were grown. Efficient optical coupling between the backbone and the teeth of the branched architecture is demonstrated by distributing light from an UV-laser-excited spot at one end of the backbone to all branch tips. By varying the deposition conditions, the orientation of the branches with respect to the backbone, their size and density can be tuned as well as the size of the backbone. This in situ seeding CVD method has the potential for a low-cost single-step fabrication of high-quality, micro/nanointegrated photonic devices, with tunable complex waveguiding possibilities.

Performance Study of a Multicast Protocol for Wireless Sensor Networks based on N 2 Connectivity

A novel object-oriented processor is proposed in this paper, which provides support for object addressing, message passing and dynamic memory management. Object running on this processor has its own control thread and communicates with others via messages. A virtual addressed object cache that reduces the indirection overhead while maintaining the efficiency of object relocation is presented. Object table that maintains the handles is used to obtain the actual object location on an object cache miss. Hardware support for explicit dynamic memory management is provided. Object allocation and deletion is strictly bounded in time. Moreover, a new concurrently dynamic memory management algorithm is proposed, which enables the processor to freely access heap during memory compaction and the applications will not be suspended for the completion of memory compaction.

LSCIC Pre-processor Design with Constriction Elucidation

This paper presents the novel behavioral architecture of LSCIC (layered scalable concurrent image compression) pre processor chip by utilizing scalable compression algorithm. This design separates enhanced and base layer pixels prior to concurrent compression operation in the coders. This paper also proposes a mathematical technique to snub the data signal errors by virtue of vector norm and eigen values by controlling matrix condition number. Before attempting the behavioral design, a mathematical model is developed with timing and control signal constraints to avoid collision of signals. Simulation and synthesis procedures with successful synthesis report are also presented to verify the effectiveness of algorithm showing the correct operation of designed architecture

Large tunable luminescence by Mn(II) aggregates in Mn-doped ZnS nanobelts

Tunable emission from the visible to infrared region in II–VI semiconductor nanostructures makes them ideal candidates for the development of optoelectronic devices. In this study, Zn1−xMnxS (x = 0.01–0.15%) nanobelts (NBs) were prepared via the chemical vapor deposition (CVD) method. The as-grown NBs were investigated by XRD and electron paramagnetic resonance (EPR). A significant lower angle shift was observed in the XRD spectra, which indicated the incorporation of Mn ions. A hyperfine interaction constant A of 68.6 G obtained from the EPR spectra confirmed that Mn2+ ions were successfully incorporated into the ZnS matrix. For higher Mn concentrations, the broadening of the EPR profile was attributed to the aggregation of Mn2+ ions. Moreover, successful Mn-ion doping in individual ZnS NBs was itentified by SEM–EDS and Raman scattering analysis. Raman spectroscopy studies revealed a red-shift at the LO phonons, confirming the presence of Mn ions in ZnS NBs. Room-temperature photoluminescence (PL) showed that the Mn concentration plays an important role in tuning the emission from 452 nm to 877.6 nm (blue to near-infrared:NIR); whereby, up to 15% Mn, PL showed emissions are centered at 447, 535, 580.7, 651.1, and 877.6 nm. Herein, the first two peaks were assigned to anti-ferromagnetic coupling of 4 Mn ions, and the interaction of 2 Mn ions with stack faults in ZnS NBs. The next peak was from the typical d–d transition (4T1(4G) → 6A1(6S)) of Mn2+, and the last two peaks were assigned to the aggregate made up of 2 Mn ions and (MnS)5 cluster-related emission with ferromagnetic coupling. NIR emission was also detected from the 10% Mn-doped CdS NBs. To the best of our knowledge, herein, NIR emission was observed for the first time in ZnS nanostructures. These kinds of nanomaterials may have potential applications in photovoltaics, telecommunications, and remote sensing.

Group delay of single-photon transmission in a waveguide side coupled with a Jaynes-Cummings chain

Using a real-space model Hamiltonian, we have theoretically studied the single-photon transmission in a waveguide side coupled with a Jaynes-Cummings chain (JCC). The JCC can induce the photon group advancement (GA) and group delay (GD) in different frequency ranges determined by JCC eigenmodes. For GA and GD, there exist different optimal JCC lengths. At certain frequency, the GAs maximum value as usual increases with decreasing the cavity dissipation, whereas the GDs eventually reaches saturation. For a 1.55 -μm photon, our calculation indicates that the GDs maximum value is about 400 ps simultaneously with a large transmission.

A Model on the Mn2+ Luminescence Band Redshift with Mn(II) Doping and Aggregation within CdS:Mn Microwires

We report the microphoto-luminescence band redshifts with individual and multi-Mn(II) ion emissions within CdS microwires. The localized exciton magnetic polarons (LEMPs) corresponding to the d—d optical transitions of Mn(II) account for this shift. This LEMP emission from the double-, three- and four-Mn(II) ions with ferromagnetic coupling after photoexcitation can happen in diluted magnetic semiconductors, except for the individual Mn(II) doping. In addition, a simple spin-exchange polaronic model is established to account for these emission peaks well. Through this model, we can verify the local geometry of the Mn(II) ions in CdS microwires.

Optimum Image Compression Techniques with Data Transform Pyramid

Digital circuits are designed and implemented with respect to time and area optimization. Particularly in the field of image processing, data is to be transmitted from source to destination with optimum conditions of quality and transmitting speed. These objectives are achieved in diverse schemes under different circumstances. This paper describes a method to deal with image compression techniques to explain various aspects of image quality improvement associated with quality controlling factors. Huffman algorithm is utilized by developing pyramid of data for encoding and decoding process. This algorithm is applied on pre and post processing architecture which operates efficiently in varying system band width conditions. Moreover, results acquired by developed code enable us to understand different important parameters those affect image quality

Prediction of cotton leaf curl virus disease and its management through resistant germplasm and bio-products

Abstract Cotton leaf curl virus disease reduces the cotton yield significantly every year and is transmitted by Bemisia tabaci. The study was designed to evaluate 15 varieties/lines against the disease. Multiple regression analysis was performed based on a-biotic environmental variables (maximum air temperature, minimum air temperature, relative humidity and rainfall) to predict disease incidence and its vector (Bemisia tabaci). Two bio-products were evaluated against the whitefly population to control the disease. Out of 15 cotton varieties/lines, no one was found highly resistant against the disease. Five varieties/lines (BT BT-980, BT-457, KIRAN, BT-666 and SLH-BT-6) exhibited moderately resistant response. Maximum air temperature (34–35.5 °C), minimum temperature (25.75–26.25 °C), relative humidity (64.14–66%), rainfall (1–2 mm) and wind speed (5.50–5.75 Kmh−1) favoured the disease development. Maximum whitefly population was favoured by maximum air temperature from 34–35.5 °C, 25.8–26.2 °C minimum air temperature, 64.14–66% relative humidity, 1–2 mm from rainfall and 5.50–5.75 Kmh−1 wind speed. Datura stramonium was found more effective as compared to Aviara (Homoeopathic) but not from the positive control (Acetamiprid).

Distortion Analysis in Scalable Image Compression Scheme based on efficient Codebook selection

Image compression scheme is divided into different operational phases for reliable, successful and efficient results. In this paper, layered scalable concurrent image compression ISCIC pre coder is analyzed which is already proved scalable and stable with respect to data transmission and pixel loss. In the light of available compression schemes associated with vector quantization, codebook is developed using different optimized techniques like pair wise nearest neighbor algorithm, and other modified methods majority of them based on Linde Buzo Gray IBG algorithm. For the accomplishment of the objective, data blocks from ISCIC pre coder reach encoder which selects best code vector with respect to similarity with input vector. Best selection is obtained by the virtue of distortion measurement by utilizing Lloyd algorithm in conjunction with vector quantization method. Results are shown to achieve some novel observations when best codebook is selected.

Task Partitioning-An Efficient Scalable Pipelined Digital Design Scheme

Digital circuits are designed after careful investigation of implementation constraints and limitations. Implemented circuits, whether realized on FPGA or an ASIC is developed, it is made sure that resulting design should be optimized with respect to processing speed and area occupied. Much informative work has been already proposed and effective results have obtained in the research field of processing speed and area optimization. In this paper, the concept of hierarchical concurrent flow graph (HCFG) is utilized to present proposed coarse grained layered scalable concurrent image compression (LSCIC) precoder design with pipelined scheme. This design causes all modules to operate concurrently for fast and minimum data loss operation. This scheme will not only highlight the task partitioning procedure to operate all modules in parallel but also gives rise to the concept of pipelining with reasonable number of stages so that system remains optimized. Moreover, practical solutions acquired by simulating tools are presented in this paper with appropriate substantiation. This paper also addresses the issue of selected FPGA resource utilization depending upon the complexity of operation and hardware components placed in corresponding module.