The Use of a Convolutional Neural Network in Detecting Soldering Faults from a Printed Circuit Board Assembly

Automatic Optical Inspection (AOI) is any method of detecting defects during a Printed Circuit Board (PCB) manufacturing process. Early AOI methods were based on classic image processing algorithms using a reference PCB. The traditional methods require very complex and inflexible preprocessing stages. With recent advances in the field of deep learning, especially Convolutional Neural Networks (CNN), automating various computer vision tasks has been established. Limited research has been carried out in the past on using CNN for AOI. The present systems are inflexible and require a lot of preprocessing steps or a complex illumination system to improve the accuracy. This paper studies the effectiveness of using CNN to detect soldering bridge faults in a PCB assembly. The paper presents a method for designing an optimized CNN architecture to detect soldering faults in a PCBA. The proposed CNN architecture is compared with the state-of-the-art object detection architecture, namely YOLO, with respect to detection accuracy, processing time, and memory requirement. The results of our experiments show that the proposed CNN architecture has a 3.0% better average precision, has 50% less number of parameters and infers in half the time as YOLO. The experimental results prove the effectiveness of using CNN in AOI by using images of a PCB assembly without any reference image, any complex preprocessing stage, or a complex illumination system. Doi: 10.28991/HIJ-2022-03-01-01 Full Text: PD

Fluorescence Lifetime Measurement using Time Correlated Single Photon Counting

A time correlated single photon counting (TCSPC) setup is built to measure the fluorescence decay of samples, such as solar cell materials. TCSPC is a sensitive technique for measuring fluorescence decays on nanosecond time scale and longer. The principle of TCSPC is based on the precise registration of the arrival time of fluorescence photons from a sample. A fluorescence decay curve is constructed from the TCSPC measurement, this curve is used to extract the fluorescence lifetime. The setup is novel with respect to the conventional method of collecting a fluorescence signal. It is a simplified setup as there is no need of complex geometry of optics to focus the excitation beam or to image the fluorescence on to the detector. Instead, the excitation beam is unfocused and the sample is placed as close to the detector as possible. This approach allows for the usage of low excitation density of photons. The low level of light that this setup could detect made it very sensitive for measuring samples with low emission. The setup is characterised with two different samples: Coumarin-152 (7-N,N-dimethylamino-4-trifluoromethyl-1,2-benzopyrone) and APFO3 (poly[2,7-(9,9-dioctylfluorene)-alt-5,5-(4,7′-di-2-thienyl-2′,1′,3- benzothiadiazole)]). Coumarin-152 is a commercial laser dye and APFO3 is a polymer solar cell material. These measurements reveal that the single and non exponential curves could be obtained using this setup. The verification of the setup is further carried out by classifying different errors that can influence the measurements.Popular Science Abstract This thesis is about the construction and demonstration of time correlated single photon counting (TSCPC) setup. The technique is essentially digital and is based on detection and counting of single photon, recognizing quantum nature of light. The time is measured between excitation pulse and detected photons and is stored in histogram with x-axis corresponding to time interval. The sample is excited repeatedly and resulting histogram of intensity versus time called as fluorescence decay curve. Generally speaking, fluorescence or emission spectroscopy is one of the fundamental spectroscopic techniques. This is the study of fluorescence phenomenon which is the emission of photons from singlet excited state. The emission is red shifted relative to absorption maxima due to loss of energy as heat during relaxation process. In the time resolved fluorescence decay experiment, the sample is excited with pulse of laser light, it starts with high intensity and then decays, rapidly. Later on from appropriate fitted functions, type of decay, lifetime and amplitudes are calculated. In case of photon counting, the measured data is in form of discrete time function. But still the fitted functions provide the same information. Then question arises about additional advantage of our TCSPC technique over other life time measurements. The additional benefits come from simplicity of integrated setup i.e. lack of focussing lenses and very low excitation density is required. The setup has been characterized by measuring the fluorescence decay from organic dye and polymer solar cell material. The data has been fitted with exponential functions and fluorescence life times are calculated with good accuracy. Other than life time measurements, the technique is being successfully used for single molecule detection, TCSPC imaging, and fluorescence correlation spectroscopy in combination with fluorescence microscopy etc

Assessment of the prevalence of Respiratory Symptoms among the Workers of Automobile Industry

Objective: To assess the prevalence of respiratory system symptoms among the workers of automobile industry who are frequently exposed to hazardous chemical agent and dust. Study Design: Cross-sectional observational study. Place and Duration of Study:  Nishtar Hospital Multan, Bahawal Victoria hospital Bahawalpur. from August 2018 to March 2019. Methodology: Sixty eight participants of which 34 were exposed and 34 were non-exposed workers of an automobile factory were selected. Age, BMI, smoking history, lung functions including FEV1, FVC, FEV1/FVC, PEF, PEF25-75 and VC before and after the work shift, symptoms including dry throat, runny nose, headache, fatigue, cough, phlegm, dyspnea, and wheeze; and chest tightness were compared between the cases and controls. Independent t-test, paired t-test and chi-square tests were applied. Data was analyzed with SPSS v.23.0 after considering p<0.05 statistically significant. Results: FEV1, PEF, and VC were significantly decreased in the exposed workers as compared those who were not exposed (p-value <0.001, <0.001 and 0.001, respectively). The decrease in FVC and FEV1/FVC and FEV1/VC ratio was also significant (p-value 0.011, 0.002 and 0.048, respectively). Dry throat, runny nose and fatigue were significantly more in cases (p-value 0.022, 0.016 and 0.018, respectively). Cough, phlegm, wheeze, and dyspnea; and chest tightness were more prevalent in the cases (p-value 0.015, <0.001, 0.001, <0.001 and 0.001, respectively). Conclusion: Decline in lung functions and prevalence of respiratory symptoms were significant in the workers exposed to dust and BTEX warranting the performance of lung function tests before and after the employment for the identification of the sensitive personnel. Keywords: automobile factories, respiratory symptoms, prevalence. DOI: 10.7176/JMPB/65-07 Publication date: April 30th 202

The Comparison of Sensitivity and Specificity of ELISA-based Microneutralization Test with Hemagglutination Inhibition Test to Evaluate Neutralizing Antibody against Influenza Virus (H1N1)

Objective: To compare the sensitivity and specificity of ELISA-based microneutralization test with hemaglutination inhibition test for the evaluation of neutralizing antibody against influenza virus (H1N1). Study Design: Nonrandomized Quasi Trail. Study Place and Study Duration: Department of Medicine, Allama Iqbal memorial teaching hospital, Sialkot and Nishtar Hospital Multan. January 2018 to May 2019. Material and methods: A total of 188 patients were enrolled in our study out of which 101 suffered from influenza type A. Serum samples were collected from different staff members during this period. ELISA based Microneutralization test was performed in 101 samples and similarly Hemagglutination assay was also performed in 101 serum samples. Tests were run twice on two separate days and final result was average of the two runs. All the data thus obtained was subjected to statistical analysis. Frequency and percentages were calculated for qualitative variables like, gender, sensitivity and specificity, while mean and standard deviation was calculated for quantitative variables like, age and BMI. Results: Both the tests were performed on all the sera samples. The sensitivity of the Hemagglutination Inhibition Test (HI) was 65.34% and the specificity was 66.51%. On the contrary, the sensitivity was 87.12% and specificity was 90.80% on the ELISA based microneutralization assay (micro NT-ELISA). As the sensitivity and specificity of the micro NT-ELISA is more than that of Hemagglutination Inhibition Test, this makes ELISA based microneutralization assay superior.Conclusion: ELISA based microneutralization test is much more sensitive and specific as compared to the hemaglutination inhibitor assay in terms of detection of neutralizing antibodies against influenza virus (H1N1). Keywords: Microneutralization, Hemagglutination, Influenza DOI: 10.7176/JMPB/65-08 Publication date: April 30th 202

Muros en movimiento: Las prácticas de producción y circulación en los nuevos medios (off-line y on-line) del street art en Lima (2018-2021)

Esta investigación se enfoca en estudiar las nuevas formas de producción, circulación y consumo del street art o arte urbano en varios distritos de Lima. La investigación se basa entre el periodo de 2018 hasta 2021 en distritos como Ate, San Juan de Lurigancho, Centro de Lima, Barranco y Miraflores. Este proyecto, que empieza como una curiosidad personal, tiene como objetivo de estudiar de qué manera un fenómeno que empieza en la calle, de qué forma se traslada al mundo virtual / digital. Como lo demostraré en el desarrollo de esta tesis, el mural en la calle enmascara una red de interacciones y negociaciones sociales detrás. Esta agencia del arte urbano se estudia teniendo como base la teoría de arte y antropología de Alfred Gell. Además, se identifican los diversos actores involucrados en el microcosmo de street art, cómo nace la acción artística en la calle, de qué manera satisfacen a la demanda de consumo de street art en Instagram y cómo un mural puede adquirir un valor socio político mientras que hay otros murales que terminan siendo meramente ‘vandalismo’. Por otro lado, se analiza la circulación del arte urbano en el mundo digital y cómo este actúa para crear un (nuevo) régimen de valor en las palabras de Appadurai y con la aplicación de Big-Data, se propone una nueva estrategia de estudiar los fenómenos online. Finalmente, se estudia el efecto de cómo la pandemia de Covid-19 ha impulsado la necesidad de reinventarse, tanto al fenómeno de street art como a los artistas como persona

Um ensaio sobre o tamanho ideal do governo: um estudo de caso do Paquistão

Pakistan is a developing country and faces the problem of the fiscal deficit since government expenditures are higher than revenues. In this situation the government has to raise loans to cover this deficit and the burden of loans and debt service is increasing significantly. Additionally, most of the budget has gone to service the debt. Under these circumstances, this study is an attempt to find the optimal size of the government and compare it with the actual size of the government. To calculate the optimal threshold level of government spending, the methodology used by Heerden (2008) for Pakistan is adopted. Finally, this study provides a guide for policymakers, either to reduce or increase the size of governme.Pakistán es un país en desarrollo y enfrenta el problema del déficit fiscal dado que los gastos del gobierno son más altos que los ingresos. Ante dicha situacion el gobierno tiene que levantar préstamos para cubrir este déficit y la carga de los préstamos y el servicio de la deuda está aumentando significativamente. Adicionalmente la mayor parte del presupuesto se ha ido para el servicio de la deuda. Bajo estas circunstancias, este estudio es un intento de encontrar el tamaño óptimo del gobierno y compararlo con el tamaño real del gobierno. Para calcular el nivel umbral óptimo de gasto gubernamental, se adopta la metodología utilizada por Heerden (2008) para Pakistán. Por último, este estudio proporciona una guía para los responsables de la formulación de políticas, ya sea para reducir o aumentar el tamaño del gobierno.O Paquistão é um país em desenvolvimento e enfrenta o problema do déficit fiscal, já que os gastos do governo são mais altos do que as receitas. Nesta situação, o governo tem de contrair empréstimos para cobrir esse déficit, e o ônus dos empréstimos e do serviço da dívida está aumentando significativamente. Além disso, a maior parte do orçamento foi para o serviço da dívida. Sob essas circunstâncias, este estudo é uma tentativa de encontrar o tamanho ideal do governo e compará-lo com o tamanho real do governo. Para calcular o nível ideal de limiar de gastos do governo, a metodologia usada por Heerden (2008) para o Paquistão é adotada. Finalmente, este estudo fornece um guia para os formuladores de políticas, seja para reduzir ou aumentar o tamanho do governo

Prevalence and factors associated with irritable bowel syndrome among medical students of Karachi, Pakistan: A cross-sectional study

BACKGROUND: Irritable bowel syndrome (IBS) and its association with stress, has not been studied among university students in Pakistan. We investigated the prevalence and the pattern of anxiety related IBS symptoms among medical students of Karachi. FINDINGS: An observational case–control study was carried out at three medical colleges of Karachi, Pakistan. Random sampling was done on 360 medical students. Data was collected using validated tools “Rome III Criteria” and “Generalized Anxiety Disorder Questionnaire”. Participants with IBS were diagnosed on the criteria having experienced abdominal discomfort at least 2–3 days/month associated with high level of anxiety. The apparent prevalence of IBS was found to be 28.3%, with a predominance of 87 (85.29%) females (85.29%) over males (14.71%). The psychological symptoms of anxiety were encountered in 57 (55.8%) participants with IBS, among which males were 15.7% and females 84.2% respectively. CONCLUSION: Students who more frequently suffer with mental stress and anxiety are more associated with IBS

Characterization of cypermethrin degrading bacteria: A hidden micro flora for biogeochemical cycling of xenobiotics

 Background: Cypermethrin is a Synthetic Pyrethroid (SP) having widespread applications in agriculture and industrial sector especially in sheep dip formulations and tanneries. Rhizoremediation offers a sustainable, environment-friendly and cost-effective means to carry out remediation of contaminated soils.Methods: Six bacterial strains were screened out and characterized at various doses of cypermethrin, heavy metal salts and antibiotics. The optimum growth conditions were determined for these bacterial isolates. The degradation of cypermethrin was confirmed through the growth of bacteria on minimal media (BHB) with cypermethrin and thin layer chromatographic analysis; retention factor values (Rf) were calculated and compared with standard Rf values.Results: Growth curve experiments revealed that three bacterial isolates were able to grow in the presence of cypermethrin. Tolerance to the high concentration of heavy metal salts (300µgmL-1) and resistance towards different antibiotics was observed in all three bacterial isolates indicating a positive correlation between pesticide degradation and tolerance to metals and antibiotics. Bacterial strains A-C1 and B-B2 were identified as Xanthomonas maltophilia and B-C2 as Acinetobacter sp. Cypermethrin degradation occurred concomitant with bacterial growth reaching an optical density (OD600) up to 0.869.Conclusion: Microbes present in rhizosphere have potential to mineralize the pesticides. A significant biodegradation of the cypermethrin was observed based on above mentioned lab parameters. These results paved the way for designing a multi-resistant bacterium that can be used to reverse the altered environment

Examining the contribution of fiscal policy on economic growth: Analytical insights from Pakistan

To better understand the influence of fiscal policy (FP) on economic growth (EG) in Pakistan, this study investigates the importance of the amount of output produced by different factors of production in Pakistan's economy. The annual time series data has been collected from the State Bank of Pakistan and World Bank Data-Base from the years (2001-2020). The Autoregressive Distributed Lag (ARDL) model is used for empirical research to assess the significant factors of EG, and the Augmented Dickey-Fuller (ADF) unit root test is used to ensure that all of the variables are stationary. Using annual time series data from 2001 to 2020. Based on these findings, this study recommends adopting a proactive fiscal policy framework that incorporates expansionary measures. We argue that this strategy has the capacity to stimulate and maintain Pakistan's economic growth path, thereby fostering a more promising and prosperous future. Moreover, the study found the impact of government expenditures (GE), gross fixed capital creation (GFCC), and direct and indirect taxes on Gross domestic Product (GDP). Additionally, findings showed that government expenditures, gross fixed capital creation, indirect, and direct taxes have a strong effect on economic growth. It is argued that an expansionary fiscal policy in the future could greatly benefit Pakistan's economic growth