Electroceramics are necessary component in modern technologies of many kinds. In this regard, barium meta-titanate (BaTiO3 or BT) based materials with ABO3 perovskite structure are potential candidates for applications in electronic devices because of their piezoelectric, ferroelectric and optical properties. Barium titanate based materials have attracted significant interest; due to their wide spread applications in wireless communication, space and defense. Barium titanate based ferroelectric materials are suitable for these applications due to their electric field dependent permittivity (εr) and low dielectric loss (tan δ) above Curie temperature (Tc). Ferroelectric materials generally have high dielectric losses, which is due to piezoelectric grain resonance and domain wall motion. It is known that Tc and dielectric properties of BaTiO3 can be systematically changed by chemical substitution at A or B-site by a wide variety of isovalent and aliovalent dopants. The effect of small additives and dopants on the dielectric properties of BaTiO3 based ceramics fabricated by conventional solid state sintering route have been investigated in detail; however, little attention have been given to sol-gel processing of ceramics for dielectric applications. In the present study, the microstructure and dielectric properties of BaTiO3- based ceramics doped with Sr, La, Zr and Mn were investigated in detail. Various compositions [BaTiO3, Ba1-xSrxTiO3 (x = 0.25, 0.35, 0.45, 0.55, 0.65), Ba1-xLaxTi1- x/4O3 (x = 0.00, 0.015, 0.025, 0.035, 0.045, 0.055), Ba0.7Sr0.3Ti1-xZrxO3 (x = 0.02, 0.04, 0.06, 0.08, 0.1), (Ba0.5Sr0.5)Mnx(Ti0.95Fe0.05)1-xO3 (x = 0.00, 0.004, 0.006, 0.008, 0.01, 0.02)] with different stoichiometric ratios were synthesized by using modified sol-gel technique. The dielectric properties of the BaTiO3-based ceramics were studied by making different compositions by substituting the above elements to form solid xvii solutions. Thermal analysis (TG/DTA) was used to trace the synthesis temperature. The temperature range from 750 oC‒900 oC was found suitable for single phase formation of the BaTiO3-based ceramics processed via sol-gel route. The phase and microstructure of the final ceramics were investigated using Xray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Fourier transform infrared spectroscopy (FTIR) was used to investigate the water content and organic functional groups in calcined samples. The dielectric properties were investigated using LCR-meter and impedance analyzer. The tetragonal symmetry (P4mm) of the BaTiO3 ceramics was confirmed by the XRD studies. XRD studies confirmed the tetragonal crystal structure of the x = 0.00 – 0.035 compositions at room temperature of the Ba1-xLaxTi1-x/4O3 ceramic samples. A cubic symmetry (Pm3m) was observed for the x > 0.035 compositions around room temperature. Analysis of the XRD data confirmed the formation of tetragonal (P4mm) phase for all the Ba0.7Sr0.3Ti1-xZrxO3 samples at room temperature. Ceramic samples of the (Ba0.5Sr0.5)Mnx(Ti0.95Fe0.05)1-xO3 showed tetragonal (P4mm) perovskite structure. Microstructure analysis of the thermally etched surface showed a heterogeneous grain growth of the BaTiO3 ceramics. The microstructure investigation revealed that La and Mn substitution acted as growth inhibitor for the BaTiO3- ceramics. Samples doped with Sr and Zr resulted in large grains with a heterogeneous microstructure. Dielectric investigation confirmed that Tc was shifted to low temperatures for the samples doped with Sr, La and Zr, while no obvious changes in the Tc was detected for the samples doped with Mn. Moreover, samples doped with Mn and Zr revealed a diffused phase transition (DPT). The impedance studies confirmed both the grain and grain boundary contributions for the BaTiO3 ceramics. For Sr-doped samples, compositions with x = 0.25 and x = 0.45 showed one xviii semicircle in the capacitance range (≈ 3.4178 × 10-10 F and 5.2016 × 10-10 F, respectively), which was associated with the grain boundary contribution. The samples with x = 0.35, 0.55 and 0.65 showed two semicircles in low and high frequency regimes, which confirmed the bulk and grain boundary contributions to the conduction mechanism. The samples doped with La showed the grain boundary contributions, only. Similarly, Zr and Mn-doped compositions showed both grain boundary and bulk contributions in the conduction mechanisms for all the samples. The total resistance (RT) was observed to decrease with increasing temperature for the pure and Sr, La, Zr and Mn doped BaTiO3 based compositions showing a typical ceramic behaviour.
متنی تنقید : انسائیکلو پیڈیا ’ امریکانا ‘ نے متنی تنقید کی تعریف کرتے ہوئے لکھا ہے : ’’ متن کے اصل الفاظ کے تعین، اسے مکمل کرنے اور واقفیت واصلیت تلاش کرنے کی غرض سے پرانی تحریروں کے سائینٹفک مطالعے کو متنی تنقید کہتے ہیں۔ ‘‘ متنی تنقید کا اصل مقصد حتیٰ الامکان متن کو اصل روپ میں دوبارہ حاصل کرنا ہوتا ہے۔ اصل روپ سے مراد وہ شکل وصورت ہے جو متن کا مصنف اپنی تحریر کو دینا چاہتا تھا۔ یعنی اگر متنی نقاد کو مصنف کے ہاتھ کا لکھا ہوا نسخہ ملا ہے تو اسے متنی نقاد من وعن ہی شائع نہیں کرسکتا کیونکہ ممکن ہے مصنف سے کچھ الفاظ چھوٹ گئے ہوں یا کچھ الفاظ دوبارہ لکھ دئیے گئے ہوں یا اس قسم کی کوئی اور غلطی ہوئی ہو۔ ایسی صورت میں متنی نقاد کا فرض ہے کہ متن کو ان غلطیوں سے پاک کرے۔ متن کے لیے ضروری ہے کہ بامعنی ہو، اگر سینکڑوں برس کے عرصے میں نقل در نقل کی وجہ سے متن مسخ ہوگیا ہے تو اس کے اصل معنی کا تعین کیا جاسکے۔ متنی تنقید/تنقیدِ متن کے مدارج : ۱۔ تیاری ۲۔ مواد کی فراہمی ۳۔ متن کی تصحیح ۴۔ قیاسی تصحیح ۵۔ اعلیٰ تنقید ۱۔ تیاری : الف۔مختلف عہد کے نسخے پڑھنا : متنی نقاد کا فرض ہے کہ مختلف عہد کی تحریروں پر عبور حاصل کرنے کے لیے ان عہدوں کے نسخے پڑھے تاکہ تحریر کی شناخت کے ساتھ ساتھ اس عہد کے الفاظ وتحریر پر اسے عبور حاصل ہوسکے۔ متنی نقاد کو اس عہد سے قبل کے کچھ نسخے بھی پڑھنے چاہئیں۔ اس انتخاب کے باقاعدہ اصول تو نہیں ہیں لیکن اس عہد میں جولوگ ادب پر چھائے ہوں ان میں سے نمایاں لوگوں کو منتخب کرلیا جائے۔ ب۔مختلف عہد کی زبان پر عبور...
Heart failure (HF) is a chronic illness with high prevalence and mortality, leading toeconomic burden ofhealth due to prolonged hospital stay and re-admissions. Failure to comprehend the importance of identifying mental illnesses could lead to explanations that why the morbidity and mortality of heart failure patients endure to be very high. Objective: To determine the frequency of anxiety and depression in heart failure patients. Methods: It is a descriptive cross sectional study including 323 CHF patients admitted to the Faisalabad Institute of Cardiology hospital, 250 were males and 73 were females, mean age was 54.1 ± 9.2 years having 70 years as maximum and 25 years as minimum. Data was collected with the help of HADS questionnaire. Patients were interviewed for assessment of anxiety and depression. Data was analyzed using SPSS version 24. Mean and standard deviation was calculated for quantitative data and for qualitative data frequency and percentageswas calculated. To measure the association of anxiety and depression with age categories and gender, chi square test was used. P values less than and equal to 0.05 were taken as significant. Results: The results showed that 43% subjects had <11 score indicating no anxiety, 57% had >11score indicating anxiety. 45% subjects had<11 score indicating no depression, 55% had >11score indicating depression. Conclusions: The study concluded that frequency of depression and anxiety is high in congestive heart failure patients. Strategies are required to assess and diagnose these mental illnesses to establish early treatment which may foster multidisciplinary health care team approach and interventions that address the psychological burden.
On-board model based condition monitoring of an automotive spark ig- nition engine is still a challenging task for automotive industry. The diagnostic system aims to enhance fuel efficiency and to reduce harmful exhaust emissions. Among various subsystems of gasoline engine, air intake system holds prime impor- tance as it is responsible to ensure proper air and fuel proportions in combustion mixture. This subsystem exhibits highly nonlinear behavior due to its components like throttle body, intake manifold etc. Health monitoring of such nonlinear system cannot be performed by conventional diagnosis methods. That is why On-Board Diagnostic (OBD-II) standard kits do not have the provision to diagnose vari- ous air intake system faults. These faults include air leakages in intake manifold, clogged air filter, reduced throttle body efficiency and certain sensor faults. This manuscript presents a novel nonlinear health monitoring scheme based on sliding mode theory for on-board diagnostics of air intake system. Sliding mode theory is extensively used in fault diagnosis methodologies. Sliding mode observers based on nonlinear dynamics deliver robust platform for the estimation of un-measurable system variables. The estimation of such parameters can be exploited for fault diagnosis of dynamical systems. In this dissertation, second order sliding mode observers are designed for air intake system. The designed observers are used to estimate un-measurable and critical parameters/states. Five of the estimated crit- ical parameters are: frictional torque, combustion efficiency, volumetric efficiency, air filter discharge coefficient and throttle discharge coefficient. These parameters are estimated from a two state nonlinear model of gasoline engine based on inlet manifold pressure and rotational speed dynamics. These parameters are extremely helpful in engine modeling, controller design and fault diagnosis/prognosis. An- other contribution of this thesis is the development of virtual sensors for air intake system. Pressure dynamics are estimated from crankshaft sensor measurements and vice-versa. The outlined parameters and virtual sensors are used to moni- tor various functions of air intake system. These functions cannot be routinely sensed/monitored by any sensor. The estimation of afore-mentioned parameters has been conducted under healthy and faulty operating conditions to generate residuals. These residuals are evaluated to identify/classify any malfunction in air intake system. A detailed procedure for three fault diagnostic schemes have been discussed. These scheme require no extra sensor/hardware for their evaluation, only conventional on-board diagnostics (OBD) equipments are mandatory. The validation of novel estimation and diagnostic scheme is performed on production vehicle engine equipped with engine control unit compliant to OBD-II standards. It has been shown experimentally that the above discussed faults have been timely identified. The proposed fault diagnosis scheme has the potential for online im- plementation as it operates sample-by-sample on OBD-II measurements.