Amir Shahzad

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Papers by Amir Shahzad

Response Surface Modeling of Physical and Mechanical Properties of Cotton Slub Yarns

Autex Research Journal, 2018

The objective of this study was to model the physical and mechanical properties of 100% cotton sl... more The objective of this study was to model the physical and mechanical properties of 100% cotton slub yarns commonly used in denim and other casual wear. Statistical models were developed using central composite experimental design of the response surface methodology. Yarn’s linear density, slub thickness, slub length and pause length were used as the key input variables while yarn strength, elongation, coefficient of mass variation, imperfections and hairiness were used as response/output variables. It was concluded that yarn strength and elongation increased with increase in linear density and pause length, and decreased with increase in slub thickness and slub length. Yarn mass variation and total imperfections increased with increase in slub thickness and pause length, whereas yarn imperfections and hairiness decreased with increase in slub length. It was further concluded that due to statistically significant square and interaction effects of some of the input variables, only the...

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Electrical Energy form Rising Air Bubbles

International Conference of Energy Harvesting, Storage, and Transfer, 2018

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Development of optimized triaxially electrospun titania nanofiber‐in‐nanotube core‐shell structure

Journal of Applied Polymer Science, 2021

An integrated geotechnical and geophysical investigation of a catastrophic landslide in the Northeast Himalayas of Pakistan

Geological Journal, 2021

Trends of Smoking Among the Parents of Congenital Talipes Equinovarus Patients

Background: Congenital Talipes Equino-Varus is one of the deformities of the lower limb that is m... more Background: Congenital Talipes Equino-Varus is one of the deformities of the lower limb that is most prevalent among males. Many epidemiological studies are in progress/going on to know the exact cause, even though it is suggested that genetic and environmental factors (smoking) play central role in causing the disorder. Objectives: To evaluate the trends of smoking, economic status, educational and ethnic background in parents of patients with Congenital Talipes Equino-Varus Methodology: The study was a descriptive cross section survey carried out at PIPOS Rehabilitation Services Program (PRSP), Peshawar from April 2014 to May 2014. A self-structured questionnaire was used to collect data from participants. Only the patients with clubfoot were included in the study. The data was analyzed by using SPSS V20. Results: Number of the participants included in the study were n=107 and Mean age was 8.22± 6.10 years. 70 (65 %) participants were having bilateral clubfeet and 37 (35%) were u...

Comment on “An ultrathin stretchable triboelectric nanogenerator with coplanar electrode for energy harvesting and gesture sensing” by X. Chen, Y. Song, H. Chen, J. Zhang and H. Zhang, Journal of Materials Chemistry A, 2017, 5, 12361

Journal of Materials Chemistry A, 2017

The electrostatic charge issue in skin-contact type triboelectric energy harvesting devices can b... more

Hybrid nanogenerator and enhancement of water–solid contact electrification using triboelectric charge supplier

Nano Energy, 2018

Abstract Artificially embedded surface charges can dramatically improve the output energy of wate... more Abstract Artificially embedded surface charges can dramatically improve the output energy of water–solid contact electrification devices, but the embedded charges easily escape or are cancelled out by adsorption of opponent ions in ambient conditions. Here, we demonstrate a hybrid energy harvesting nanogenerator by combing water–solid and solid–solid contact electrification schemes. It consists of a water–solid contact electrification device and wind-fluttering ribbons that regularly supplies triboelectric surface charges on the solid surface and hence, the high density of surface charges can remain on the surface. This scheme can enhance the harvesting energy by up to a factor of 30 during rain. Moreover, the fluttering ribbons independently collect electric energy from mild winds without rain. This scheme provides a facile, cost-effective, and robust approach to enhance the energy-harvesting efficiency of a water–solid contact electrification device and to combine the energy harvesting from simultaneous rain and wind.

Enhanced filtration and comfort properties of nonwoven filtering facepiece respirator by the incorporation of polymeric nanoweb

Polymer Bulletin, 2019

Protection for the respiratory system has become a need of the day due to increased air pollution... more Protection for the respiratory system has become a need of the day due to increased air pollution. Different nonwoven filter media have been incorporated into filtering facepiece respirators (FFRs). However, the performance of these systems could be improved further by the addition of finer nanowebs. The effect of the addition of intermediate media (nanowebs) on the comfort of FFRs also needs to be studied, as comfort can affect the performance of wearer. In this study, electrospun polymeric nanowebs were incorporated between layers of commercially available nonwoven fabrics to improve its filtration performance. The effect of the addition of polymeric webs between the layers of nonwoven filter media on the comfort properties was also studied. It was concluded that the addition of nanowebs remarkably improved the filtration capability of filter media. Also, it was found to have mixed impact on comfort properties of the resultant composite filter media; air permeability was reduced from 58 to 50 mm/s, while the filtration efficiency was improved along with thermal and water vapor permeability. Thermal conductivity was increased from 30.5 to 39 [(W/cm °C) × 104]. Water vapor permeability increased from 1.70 to 2.04 [(g/s mm2) × 108].

Improved Material Recognition Using Neural Networks

Proceedings of the 2nd International Conference on Advances in Artificial Intelligence - ICAAI 2018, 2018

Material recognition is a significant subtask in computer vision that has many different applicat... more Material recognition is a significant subtask in computer vision that has many different applications like autonomous cars in transport engineering, auto-lifting in robotics and even for some sort of autonomous-surgeries in medical field. In this paper, we suggest an improved method to recognize the materials of different categories from one photo image that is captured in an unidentified illumination and view-angle. For that purpose, several different features that cover dynamic material appearance in detail and all gathered information will be used by neural network for recognition. Our proposed method significantly improved in contrast to several leading alternatives including SIFT, Color SIFT, LBP, k-mean, and others. Additionally, we use a material database of Flickr Material Database (FMD) to analyze our method for identifying materials of different categories including foliage, plastic, wood, glass, leather, metal, paper, fabric, water and stone.

Integration of multiple bubble motion active transducers for improving energy-harvesting efficiency

Energy, 2018

Abstract In energy-harvesting systems that collect energy from waste micromechanical energy, the ... more Abstract In energy-harvesting systems that collect energy from waste micromechanical energy, the integration of multiple systems is essential to improve the total harvesting energy. However, we found that a simple integration of multiple systems does not work in water–solid electrification systems working in water, such as bubble motion active transducers (BMATs), unlike their use for typical triboelectric nanogenerators. The difference comes from the presence of water, which acts as a conductor and increases the total capacitance in the electrode with the increase in the number of systems, reducing the electrification efficiency. We systematically investigate the underlying mechanism and suggest a method to integrate multiple BMAT systems without losing energy by introducing an individually rectified multi-electrode (IRME) circuit. The rectifiers in IRME provide two functions: the usual rectifier function and an isolation function that disconnects neighboring electrodes. We demonstrate that the IRME BMAT improves the energy harvesting efficiency by a factor of the number of integrated electrodes, and that the system connecting ten electrodes works well as a power source to light an LED brightly in-situ. This method provides a promising path to the development of actual BMAT applications.

Fabrication of antibacterial electrospun cellulose acetate/ silver-sulfadiazine nanofibers composites for wound dressings applications

Polymer Testing, 2018

Abstract Metals and their nanoparticles, sodium alginate, honey and bacterial cellulose were wide... more Abstract Metals and their nanoparticles, sodium alginate, honey and bacterial cellulose were widely used in the fabrication of scaffolds and wound dressings due to their biocompatibility, but silver sulfadiazine (SSD) is a leading topical antibacterial agent especially for the treatment of burn wound infections. In this novel research study, first time SSD was embedded with nanofibers. The objective of this study was to fabricate the wound dressings by blending of SSD with cellulose acetate (CA) for high profiled antibacterial properties. The resultant electrospun CA/SSD nanofibers revealed the appreciable morphology with uniform blending of SSD in the CA/SSD nanofibers. SEM images showed that the average diameter distribution of CA/SSD nanofibers was uniform with 292 ± 2, 287 ± 4, 293 ± 3 and 286 ± 6 nm. FT-IR spectra revealed that CA/SSD nanofibers having strong chemical interactions between SSD and CA. The XRD spectra and water contact angle test also showed that CA/SSD nanofibers revealed the suitable water absorbency as required for scaffoldings. The resultant CA/SSD nanofibers exhibited the appreciable antimicrobial activity against Gram-negative Escherichia Coli and Gram-positive Bacillus Subtilis bacteria with considerable sustainability for repetitive use. So, CA/SSD nanofibers can be used as a promising & distinguish product for wound dressings applications.

Preparation and characterizations of multifunctional PVA/ZnO nanofibers composite membranes for surgical gown application

Journal of Materials Research and Technology, 2018

Abstract Herein, we developed the multifunctional; antibacterial, ultraviolet rays (UV) protected... more Abstract Herein, we developed the multifunctional; antibacterial, ultraviolet rays (UV) protected and self-cleaning surgical gown by blending of zinc oxide (ZnO) nanoparticles with poly vinyl alcohol (PVA). For this objective, ZnO NPs were blended in three different concentrations: 5 wt%, 7 wt% and 9 wt% in 10 wt% of PVA solution. The morphology of resultant nanofibers was observed under scanning electron microscope and transmission electron microscope and these studies showed the bead-free nanofibers and good dispersion of nanoparticles on nanofibers. Fourier Transform Infrared spectroscope was used for chemical interactions, wide-angle X-ray diffraction (WAXD) was used for analyzing the crystalline structure, agar diffusion plate method was used for antibacterial activity and it showed the effective response of bacteria killing. UV transmission analysis was done by Ultraviolet transmission analyzer, photo-catalytic activity was done by the solar simulator, stress–strain behavior was studied by tensile strength, and water contact angles measurements were done by contact angle meter. On the behalf of characterization results, PVA/ZnO nanofibers were exhibited the desired objectives for the surgical gown. This multifunctional surgical gown is beneficial for medical surgeon against the bacteria, stains and UV blocking to save his/her life.

In vitro assessment of dual-network electrospun tubes from poly(1,4 cyclohexane dimethylene isosorbide terephthalate)/PVA hydrogel for blood vessel application

Journal of Applied Polymer Science, 2018

Cirrhotic Patients; Prevalence of Portal Hypertensive Gastropathy Undergoing Upper Gastrointestinal Endoscopy at a Tertiary Care Hospital in Shaheed Benazeerabad

THE PROFESSIONAL MEDICAL JOURNAL, 2016

The aim behind this study was to determine the prevalence of portal hypertensive gastropathy in c... more

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Electrowetting in a water droplet with a movable floating substrate

Physical Review E, 2016

Electrowetting (EW) enables facile manipulation of a liquid droplet on a hydrophobic surface. In ... more Electrowetting (EW) enables facile manipulation of a liquid droplet on a hydrophobic surface. In this study, manipulation of an electrolyte droplet having a small floating object on it was investigated on a solid hydrophobic substrate under the EW process. Herein, the floating object exhibited a vertical motion under an applied electric field owing to the spreading and contraction of the droplet on its connecting substrates. The field-induced height variation of the floating object was significantly influenced by the thicknesses of the dielectric and hydrophobic materials. A small mass was also placed on the top floating object and its effect on the spreading of the droplet was observed. In this system, the height of the top floating object is precisely controllable under the application of an electric voltage. The proposed system is expected to be highly useful in the design of nano- and micro-oscillatory systems for microengineering.

Altered cast Technique: Improving Tissue support for the Distal Extention Bases

Altered cast impression technique is commonly used for the mandibular distal extension partially ... more Altered cast impression technique is commonly used for the mandibular distal extension partially dentulous arches. The technique is relatively simple but requires increased chair-side time and laboratory cost. Oral tissues that have been displaced during the impression procedure attempt to regain the anatomic form and they may get inflamed if the denture base does not permit them to do so. The aim of this case report is to portray an approach of recording a minimal tissue displacing altered cast impression using addition cured silicone material.

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A Review on Subcutaneous Veins Localization Using Imaging Techniques

Current Medical Imaging Reviews, 2014

More Flops or More Precision? Accuracy Parameterizable Linear Equation Solvers for Model Predictive Control

2009 17th IEEE Symposium on Field Programmable Custom Computing Machines, 2009

In this paper we exploit FPGA flexibility in the context of accelerating the solution of many sma... more In this paper we exploit FPGA flexibility in the context of accelerating the solution of many small systems of linear equations, a problem central to model predictive control (MPC). The main observation exploited by this work is the distinction between accuracy (meaning the degree of correctness of a final computational result) and precision (meaning the degree of correctness of each atomic computation) [1]. Using iterative methods for solving linear systems, one can obtain improved accuracy either by running more iterations or by using more precise internal computations, unlike direct methods, where accuracy is only a function of operation precision. Thus, in iterative methods, for a given accuracy requirement we may conduct fewer iterations in a higher precision, or more in a lower precision. We argue that this suits FPGA architectures ideally, as low precision operations result in greater parallelism for any fixed area constraint. We show that we may therefore optimize the performance by balancing iteration count and operation precision, resulting in a several-fold speed improvement over a double-precision implementation, but with the same final result accuracy. Exploring this trade-off it is possible to provide a speed-up of 26× on average, 14× in the worst case and 36× in the best, compared to a high-end CPU running at 3.0 GHz. This has the potential to allow modern highperformance control techniques to be used in novel settings such as aircraft and diesel engines.

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A Stable and Efficient Method for Solving a Convex Quadratic Program with Application to Optimal Control

SIAM Journal on Optimization, 2012

A method is proposed for reducing the cost of computing search directions in an interior point me... more A method is proposed for reducing the cost of computing search directions in an interior point method for a quadratic program. The KKT system is partitioned and modified, based on the ratios of the slack variables and dual variables associated with the inequality constraints, to produce a smaller, approximate linear system. Analytical and numerical results are included that suggest the distribution of eigenvalues of the new, approximate system matrix is improved, which makes it more amenable to being solved with an iterative linear solver. For this purpose, new preconditioners are also presented to allow iterative methods, such as MINRES, to be used. Numerical results indicate that the computational complexity of the proposed method scales well when applied to a finite horizon discrete-time optimal control problem with linear dynamics, quadratic cost, and linear inequality constraints, which arises in model predictive control applications.

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An efficient algorithm for the solution of a coupled Sylvester equation appearing in descriptor systems

Automatica, 2011

Descriptor systems consisting of a large number of differential-algebraic equations (DAEs) usuall... more Descriptor systems consisting of a large number of differential-algebraic equations (DAEs) usually arise from the discretization of partial differential-algebraic equations. This paper presents an efficient algorithm for solving the coupled Sylvester equation that arises in converting a system of linear DAEs to ordinary differential equations. A significant computational advantage is obtained by exploiting the structure of the involved matrices. The proposed algorithm removes the need to solve a standard Sylvester equation or to invert a matrix. The improved performance of this new method over existing techniques is demonstrated by comparing the number of floating-point operations and via numerical examples.

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