Papers by Muhammad Irfan Haider
Bias Correction of Mixed Distributions of Temperature with Strong Diurnal Signal
Weather and Forecasting, 2022
The performance of first-moment and full-distribution bias-correction methods of monthly temperat... more The performance of first-moment and full-distribution bias-correction methods of monthly temperature distributions for seasonal prediction is analyzed by comparing two approaches: the standard all-in-data procedure and the 6-hourly stratification of data. Five models are applied to remove the systematic errors of the CFSv2 forecasts of temperature for the rainy season in the Ethiopian Blue Nile River basin domain. Using deterministic evaluation measures, it is found that the stratification marginally increases the forecast skill especially in regions where the data distribution of temperature is prominently multimodal. The improvement may be attributed to a split of the mixed distribution into a set of unimodal distributions. A necessary condition for this splitting into unimodal distributions is that the amplitude of the diurnal cycle be larger than the interannual variability in the sample. The maximum improvement of stratification is achieved by the first-moment correction model....
Quantification of the mechanical strength of thermally reduced graphene oxide layers on flexible substrates
Engineering Fracture Mechanics, Feb 1, 2021
Abstract This paper proposes a method to characterize the failure modes of rGO 1 -based devices u... more Abstract This paper proposes a method to characterize the failure modes of rGO 1 -based devices using a controlled peel test. Analysis of the detached rGO particles from the substrate during testing was performed with an image processing technique and results were used to create a mathematical model quantifying the cohesion and adhesion failure energies. Partial failure energies were calculated based on percentage of rGO particles detached from the substrate so that the higher detachment percentage the lower failure energies. The model was applied to an array of tests on samples made with different GO concentrations, preparations, and treatments.
Ethylenediamine Vapors‐Assisted Surface Passivation of Perovskite Films for Efficient Inverted Solar Cells
Solar RRL
Materials
Self-healing materials have the potential to create a paradigm shift in the life cycle design of ... more Self-healing materials have the potential to create a paradigm shift in the life cycle design of engineered structures, by changing the relation between material damage and structural failure, affecting structures’ lifetime, safety, and reliability. However, the knowledge of self-healing capabilities in metallic materials is still in its infancy compared to other material systems because of challenges in the synthesis of organized and complex structures. This paper presents a study of a metal matrix composite system that was synthesized with an off-eutectic Tin (Sn)-Bismuth (Bi) alloy matrix, reinforced with Nickel–Titanium (NiTi) shape memory alloy (SMA) wires. The ability to close cracks, recover bulk geometry, and regenerate strength upon the application of heat was investigated. NiTi wires were etched and coated in flux before being incorporated into the matrix to prevent disbonding with the matrix. Samples were subjected to large deformations in a three-point bending setup. Sub...
Awareness about the climate impact of air conditioning systems has given impetus in developing en... more Awareness about the climate impact of air conditioning systems has given impetus in developing environment-friendly solutions. The transcritical CO 2 cycle with an ejector as a work recovery device has been reported as one of the green solutions in the literature. However, commercial applicability of these systems is limited so far despite their offered potential. One of the major impediments for limited commercial usage is unavailability of a systematic approach for system design that can help system designers in finding the optimum component combination for their application. For materializing system design approach, it is imperative to develop a system model that can accurately predict performance for wide range of operating conditions while considering different possible component combinations. In this paper, an ejector system model is developed using individual component models of ejector, evaporator, and compressor. The ejector is being modeled using the ejector performance maps, a recently developed methodology for representing ejector performance of a fixed-geometry ejector. The ejector performance maps are accurate, yet they can predict ejector performance for wide range of operation. The evaporator is modeled using geometric parameters, and the refrigerant and the air-side operating conditions, whereas other heat exchangers are modeled using thermodynamic state analysis. The compressor is modeled using semi-empirical correlations by curve-fitting tencoefficient polynomial using compressor speed and pressure ratio as characterizing variables. The system analysis considers a total of eight component combinations for transcritical CO2 ejector cycle and helps in finding the combination that gives the optimum performance. The results are encouraging as the system analysis using ejector performance maps can help in designing new improved systems. The methodology can also be tested for designing ejector air conditioning systems using other refrigerants.
Surface modification of CsPbI2Br for improved performance of inorganic perovskite solar cells
Physica E: Low-dimensional Systems and Nanostructures
Viruses always have profound effect on the growth and development of plants and interact with hos... more Viruses always have profound effect on the growth and development of plants and interact with host defense <br> mechanism and results in altering the physiology of plants. In the present study effect of different whitefly <br> transmitted begomoviruses; (monopartite as well as bipartite) on the contents of soluble sugar and chlorophyll of <br> Lycopersicon esculentum and Nicotiana benthamiana plants were investigated. It was found that the leaf relative <br> water contents (RWC), total soluble sugars (TSS), fresh and dry biomass, photosynthetic pigments level were <br> more in healthy plants as compared to virus infected plants. Plant infected both with Tomato leaf curl new dehli <br> virus and Cotton leaf curl burewalla virus associated with betasatelite showed reduced TSS and leaf relative <br> water contents as compared to healthy plants. Among infectious clones Cotton leaf curl burewalla virus <br> associated with beta satellite (C...
Modulating defect density of NiO hole transport layer via tuning interfacial oxygen stoichiometry in perovskite solar cells
Solar Energy, 2022
Challenges and Strategies in Teaching Linear Algebra, 2018
This study examines students' reasoning about eigenvalues and eigenvectors as evidenced by their ... more This study examines students' reasoning about eigenvalues and eigenvectors as evidenced by their written responses to two open-ended response questions. This analysis draws on data taken from 126 students whose instructors received a set of supports to implement a particular inquiry-oriented instructional approach and 129 comparable students whose instructors did not use this instructional approach. In this chapter, we offer examples of student responses that provide insight into students' reasoning and summarize broad trends observed in our quantitative analysis. In general, students in both groups performed better on the procedurally oriented question than on the conceptually oriented question. The group of students whose instructors received support to implement the inquiry-oriented approach outperformed the other group of students on the conceptually oriented question and performed equally well on the procedurally oriented question. Keywords Eigenvalues ⋅ Eigenvectors ⋅ Linear algebra ⋅ Inquiry-oriented instruction ⋅ Student thinking Linear algebra is a mandatory course for many science, technology, engineering, and mathematics (STEM) students. The theoretical nature of linear algebra makes it a difficult course for many students because it may be their first time to deal with abstract and conceptual content (Carlson, 1993). Carlson (1993) also posited that this difficulty arises from the prevalence of procedural and computational emphases
First Report of Cochliobolus Australiensis Causing Leaf Spot of Bermudagrass in Pakistan
Journal of Plant Pathology, 2013
Bermuda grass (Cynodon dactylon) plants showing symptoms of light brown to blackish leaf spots we... more Bermuda grass (Cynodon dactylon) plants showing symptoms of light brown to blackish leaf spots were observed during spring 2012 in the parks and grassy lawns of Lahore (Pakistan). Samples from infected plants were collected and a fungus consistently isolated on potato dextrose agar (PDA) at 28±1°C. The fungus was identified as Bipolaris dactylon (telomorph Cochliobolus australiensis) based on its morphological and molecular features. The pathogen identity was verified by the First Fungal Culture Bank of Pakistan (FCBP) and a culture deposited (accession No. FCBP-1288). In addition, the fungal DNA was isolated and the internally transcribed spacer (ITS) region amplified (White et al., 1990), cloned, sequenced and deposited in GenBank (accession No. HE962033). Sequencing of the ITS region of ribosomal DNA showed a 99.8% nucleotide sequence identity with C. australiensis isolates from Texas (HQ608034) and India (AY923860), respectively. Reproduction of symptoms in inoculated healthy pl...
Development of a New Ejector Performance Map for Design of an Automotive Air Conditioning System
Reciprocating compressors commonly used in break systems of trucks and buses are one of the major... more Reciprocating compressors commonly used in break systems of trucks and buses are one of the major sources of noise and vibration. At design stage it is very important to find the optimum cross sectional area and the profile for discharge hole on the intermediate plate. In this study, the noise and the vibration characteristics of a single cylinder, reciprocating piston compressor used in break systems of heavy-vehicles are investigated and the results are compared for four different constructions of a compressor discharge port. A number of noise and vibration measurements are made at several operating conditions using four different intermediate plates for the same compressor. The results presented in this paper have demonstrated the effects of the cross sectional area and the profile of discharge hole in terms of the noise and the vibration levels of compressor.
Objectives: To review the aetiology, presentation and outcomes of acute pancreatitis over a perio... more Objectives: To review the aetiology, presentation and outcomes of acute pancreatitis over a period of three years. Study Design: Observational study Place and Duration of Study: This study was conducted at the Department of General Surgery, Combined Military Hospital Sialkot Cantonment from Aug 2012 to Jul 2015. Patients and Methods: This was a prospective study from a general surgery unit. The patients included had confirmed acute pancreatitis. Possible aetiology, clinical presentation, complications and the outcome were documented. Results: One hundred and twenty cases of acute pancreatitis were recorded in three years. Male to female ratio was 1 : 2.1. Mean age was 46.03 + 9.777. Gallstone disease was noted in 76.6% while alcohol ingestion in 15.8%. All the patients had epigastric pain with 66.6% of patients having radiation to the back. Serum amylase was raised in all the cases with a mean of 1331.17 U/L + 533.761. Ultrasound was diagnostic in 74.1% cases, while the CT scan pe...
Heat transfer analysis of micropolar hybrid nanofluid over an oscillating vertical plate and Newtonian heating
Journal of Thermal Analysis and Calorimetry, 2021
The unsteady flow of micropolar hybrid nanofluids through an oscillating vertical plate having in... more The unsteady flow of micropolar hybrid nanofluids through an oscillating vertical plate having infinite length has been analyzed in this study. This flow goes through Newtonian heating and thermal radiation. To enrich the thermal properties, we add copper and alumina nanoparticles to micropolar fluid. For the enhancement of heat transfer, water is taken as base liquid. The dimensionless reduced form of the governing equations for velocity, temperature and microrotation is formed by using dimensional analysis. We used Laplace transform method to have the exact solutions of these governing equations. MathCad’s software has been used to visualize the effects on the flow of fluid graphically. We found that microrotation, velocity and temperature are inversely proportional to Prandtl number but directly proportional to Grashof number. Further, temperature can be enhanced for increasing value of Newtonian heating, radiation and volume fraction of nanoparticles copper and alumina.
Solar Energy, 2020
Caesium based inorganic halide perovskite are promising alternatives to address the degradation i... more Caesium based inorganic halide perovskite are promising alternatives to address the degradation issue of the organic-inorganic hybrid halide perovskites. However, high iodine content in these inorganic perovskites leads to structural instability upon exposure to moisture. In this work, the stoichiometry of CsPbI 2 Br perovskite is slightly tuned and its effect on structural stability and device performance is studied. Afterward, the charge transport layers are optimized to improve the charge extraction in perovskite solar cells. Finally, the device performance is further improved via interfacial modification. The optimized device yielded a power conversion efficiency (PCE) of 9.7%.
Development of Ejector Performance Map for Predicting Fixed-geometry Two-phase Ejector Performance for Wide Range of Operating Conditions
International Journal of Refrigeration, 2021
Abstract Recent studies have expanded the operational envelope of ejector by utilizing both press... more Abstract Recent studies have expanded the operational envelope of ejector by utilizing both pressure recovery and liquid recirculation mechanisms. This necessitates finding a consistent representation of fixed-geometry ejector performance data using only operational variables for predicting ejector performance. Taking inspiration from the compressor performance maps, the study explores the appropriate motive, performance, and characterization variable for representing ejector performance while conducting experiments on a transcritical CO2 ejector system. The existing ejector efficiency is revisited by conducting ejector power analysis. Two possible motive variables, along with a new ejector efficiency is introduced. The trends of existing and new ejector efficiencies are studied in controlled motive variable experiments while changing suction flow conditions. The ejector performance can be represented with the help of a single curve, termed as ejector performance map, using the new ejector efficiency as performance variable and the volumetric entrainment ratio as characterization variable. The prediction accuracy for both the single-phase and the two-phase suction inlet conditions are evaluated while developing performance map using only the single-phase suction inlet data points. The methodology can predict 89.3% of the data within 20% accuracy. The applicability of the methodology is assessed for other datasets involving different refrigerants, cycle architectures, and applications. The proposed ejector performance map can be utilized in numerical ejector system analysis for investigating new cycle architectures based on ejector experimental data, thus, improving system model fidelity. It can also help system design engineers in making ejector system selection decisions after thorough system performance analysis.
Heat Transfer, 2020
The present study is aimed to analyze the unsteady micropolar nanofluid flow passing over an osci... more The present study is aimed to analyze the unsteady micropolar nanofluid flow passing over an oscillating infinite vertical plate. The flow is affected by thermal radiation and Newtonian heating. Single-walled carbon nanotubes (SWCNTs) are added to enrich the thermal properties of the micropolar fluid. Kerosene is taken as the base liquid to enhance heat transfer. By using dimensional analysis, the governing equations for temperature, velocity, and microrotation are reduced to dimensionless form and after that, these equations have been solved by applying Laplace transform method to get the exact solutions. Finally, we have presented the effects of material and flow parameters and illustrated graphically by the Mathcad software. We found that microrotation, temperature, and velocity are decreasing functions of Prandtl number but have shown increasing behavior for Grashof number. Furthermore, we found that SWCNTs-water-based nanofluid has a comparatively higher heat transfer rate than SWCNTs-kerosene and SWCNTs-engine oil-based nanofluids.
A case report of the diagnosis of Long Term Sequelae of West Nile Neuroinvasive Disease in a pati... more A case report of the diagnosis of Long Term Sequelae of West Nile Neuroinvasive Disease in a patient with 9 years history. Empirical data of symptoms and test reports has been presented and based on the available data likely pathogenesis of the disease has been discussed. The empirical data has been compared to the published literature to reach a highly confident diagnosis.
ACS Applied Materials & Interfaces, 2020
Organic solar cells based on nonfullerene acceptors have recently witnessed a significant rise in... more Organic solar cells based on nonfullerene acceptors have recently witnessed a significant rise in their power conversion efficiency values. However, they still suffer from severe instability issues, especially in an inverted device architecture based on the zinc oxide bottom electron transport layers. In this work, we insert a pyrene-bodipy donor−acceptor dye as a thin interlayer at the photoactive layer/zinc oxide interface to suppress the degradation reaction of the nonfullerene acceptor caused by the photocatalytic activity of zinc oxide. In particular, the pyrene-bodipy-based interlayer inhibits the direct contact between the nonfullerene acceptor and zinc oxide hence preventing the decomposition of the former by zinc oxide under illumination with UV light. As a result, the device photostability was significantly improved. The π−π interaction between the nonfullerene acceptor and the bodipy part of the interlayer facilitates charge transfer from the nonfullerene acceptor toward pyrene, which is followed by intramolecular charge transfer to bodipy part and then to zinc oxide. The bodipy-pyrene modified zinc oxide also increased the degree of crystallization of the photoactive blend and the face-on stacking of the polymer donor molecules within the blend hence contributing to both enhanced charge transport and increased absorption of the incident light. Furthermore, it decreased the surface work function as well as surface energy of the zinc oxide film all impacting in improved power conversion efficiency values of the fabricated cells with champion devices reaching values up to 9.86 and 11.80% for the fullerene and nonfullerene-based devices, respectively.
This paper presents a statistical model to show the dependence of cytoplasmic temperatures on the... more This paper presents a statistical model to show the dependence of cytoplasmic temperatures on the vibrational kinetic energies of molecules in a eukaryotic cell nucleus. The probability distribution 𝑃(𝐸_𝑁) of energy states of cell nucleus 𝐸_𝑁 is derived using canonical ensemble framework and the vibrational energies of molecules are quadratic function of Temperature. It has been postulated that vibrational energies changes the reaction potentials of processes making certain reactions favorable. These favorable reactions explains the evolutionary processes such as mutation at molecular level. Natural Selection is simply just favorable reactions of molecules affected by the surrounding Temperature. The effect of temperature on vibrational energies of molecules can be effectively used to study cancerous mutations and astrobiology.
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Papers by Muhammad Irfan Haider