This work presents a comprehensive comparison of switchable electromechanical transducers in an A... more This work presents a comprehensive comparison of switchable electromechanical transducers in an AlN/GaN heterostructure toward the goal of reconfigurable RF building blocks in next-generation ad hoc radios. The transducers’ inherent switching was achieved by depleting a 2D electron gas (2DEG) channel, allowing an RF signal launched by interdigital transducers (IDTs) to effectively excite the symmetric (So) Lamb mode of vibration in the piezoelectric membrane. Different configurations for applying DC bias to the channel for electromechanical actuation in the piezoelectric are discussed. Complete suppression of the mechanical mode was achieved with the transducers in the OFF state. Equivalent circuit models were developed to extract parameters from measurements by fitting in both ON and OFF states. This is the first time that an extensive comparative study of the performance of different switchable transducers in their ON/OFF state is presented along with frequency scaling of the reso...
An autonomous experimentation platform in manufacturing is supposedly capable of conducting a seq... more An autonomous experimentation platform in manufacturing is supposedly capable of conducting a sequential search for finding suitable manufacturing conditions for advanced materials by itself or even for discovering new materials with minimal human intervention. The core of the intelligent control of such platforms is the policy directing sequential experiments, namely, to decide where to conduct the next experiment based on what has been done thus far. Such policy inevitably trades off exploitation versus exploration and the current practice is under the Bayesian optimization framework using the expected improvement criterion or its variants. We discuss whether it is beneficial to trade off exploitation versus exploration by measuring the element and degree of surprise associated with the immediate past observation. We devise a surprisereacting policy using two existing surprise metrics, known as the Shannon surprise and Bayesian surprise. Our analysis shows that the surprise-reacti...
European Journal of Medical and Health Sciences, 2019
Bangladesh is a small South-Asian country at the threshold of an amazing opportunity. Due to the ... more Bangladesh is a small South-Asian country at the threshold of an amazing opportunity. Due to the relatively young age of the population, there is a tremendous possibility of economic development. However, this euphoria of demographic dividend often masks the fact that there is a time limit on this opportunity and as this population gets older, we will have a completely different age structure by 2050 with more people on the other side of 65. That will create a substantial burden on our support structure and additional budget will be needed to cater to the demands of the elderly. But if we can play our cards right, then it is possible to manage that while sustaining the development curve. But we have to act now; otherwise, it will be too late.
This study examines the role of macroeconomic uncertainty and public expenditure in determining p... more This study examines the role of macroeconomic uncertainty and public expenditure in determining private fixed investment in Pakistan. It is found that individual series are nonstationary. There is a long-run relationship between private fixed investment, public consumption expenditure, public development expenditure, and market activities. It is revealed that public development expenditure stimulates private investment, whereas public consumption expenditure is detrimental to private investment. The preferred dynamic private fixed investment function confirms that in the short run, public development expenditure enhances private investment. Moreover, macroeconomic instability and uncertainty depresses private investment in Pakistan.
Abstract At low temperatures the proton magnetic resonance signals of coordinated acetonitrile in... more Abstract At low temperatures the proton magnetic resonance signals of coordinated acetonitrile in the solutions of some group (III) and group (V) representative element halides and of Ga +3 ion can be distinguished from those of bulk acetonitrile. From the relative intensities of these signals the solvation numbers of the metal halides and Ga +3 ion were determined. Reduction in the solvation number of some complexes from the expected value was observed and is explained in terms of contact ion-pair formation. The spectrum of Ga +3 ion solution contains two distinctive signals for coordinated acetonitrile. The relative intensities of these signals vary with temperature but are independent of concentration. This is explained in terms of an equilibrium between two kinetically distinguishable solvated Ga +3 species. From the temperature dependence of the proton relaxation rates the solvent exchange parameters k 1 , δH DG and δS ‡ were calculated for various systems. Variations in the kinetic parameters among the different complexes are discussed in terms of the structure of the complex and the effect of anion participation in the coordination sphere of the complex.
IEEE Journal on Selected Areas in Communications, 2016
This paper studies stochastic power control problems over a fading channel, where the transmitter... more This paper studies stochastic power control problems over a fading channel, where the transmitter randomly harvests renewable energies from environment and stores them in a battery for future data transmissions. Moreover, data packets are assumed to arrive at the data queue of transmitter with constant rate μ. To incorporate delay quality-of-service guarantees, two delay constraint models are separately considered, namely average delay model with maximum average delay constraint and statistical delay model with maximum delay outage probability constraint. Under each delay constraint model, the stochastic power control problem aims at maximizing μ considering the randomness of channel fading and energy harvesting (EH) processes. The resulting optimization problems can be formulated as infinite-horizon Markov decision processes. Under average delay model, the optimal power control policy needs to keep track of current data queue-length state in addition to the battery state. On the other hand, under statistical delay model, a sufficiently large queue-length region is assumed, hence, the optimal policy does not depend on the data queue-length state. We study various structural properties of the optimal control policies and develop online power control algorithms that converge to the optimal solutions without requiring statistical knowledge of channel fading and EH processes. By defining and learning the so-called post-decision state-value functions, the proposed learning algorithms require less complexity and converge faster than the conventional reinforcement learning algorithms. Numerical results demonstrate the effectiveness of the online learning algorithms for different delay constraint models and EH settings.
Journal of Ayub Medical College, Abbottabad : JAMC
The mandibular foramen is of particular importance to the dentist and dental specialist as it mar... more The mandibular foramen is of particular importance to the dentist and dental specialist as it marks the beginning of the mandibular canal, which transmits inferior alveolar nerve and vessels. The aim of this study was the localization of anteroposterior and superioinferior position of the mandibular foramen on the panoramic radiographs in adolescent and young adult in a selected sample of Pakistani population. This cross Sectional study was conducted in the Orthodontic department of Dr Ishrat ul ebad khan institute of oral health science, Dow University Karachi. Material comprised 150 panoramic radiographs. The radiographs were traced on a cellophane sheet. Landmarks were marked and measurements from the centre of the mandibular foramen to other landmarks were recorded. All measurements were recorded to the nearest millimetre. The mandibular foramen occupies the posterior portion of middle third on antero-posterior width of mandible. A ratio between the sides of one or almost one in...
This work presents a comprehensive comparison of switchable electromechanical transducers in an A... more This work presents a comprehensive comparison of switchable electromechanical transducers in an AlN/GaN heterostructure toward the goal of reconfigurable RF building blocks in next-generation ad hoc radios. The transducers’ inherent switching was achieved by depleting a 2D electron gas (2DEG) channel, allowing an RF signal launched by interdigital transducers (IDTs) to effectively excite the symmetric (So) Lamb mode of vibration in the piezoelectric membrane. Different configurations for applying DC bias to the channel for electromechanical actuation in the piezoelectric are discussed. Complete suppression of the mechanical mode was achieved with the transducers in the OFF state. Equivalent circuit models were developed to extract parameters from measurements by fitting in both ON and OFF states. This is the first time that an extensive comparative study of the performance of different switchable transducers in their ON/OFF state is presented along with frequency scaling of the reso...
An autonomous experimentation platform in manufacturing is supposedly capable of conducting a seq... more An autonomous experimentation platform in manufacturing is supposedly capable of conducting a sequential search for finding suitable manufacturing conditions for advanced materials by itself or even for discovering new materials with minimal human intervention. The core of the intelligent control of such platforms is the policy directing sequential experiments, namely, to decide where to conduct the next experiment based on what has been done thus far. Such policy inevitably trades off exploitation versus exploration and the current practice is under the Bayesian optimization framework using the expected improvement criterion or its variants. We discuss whether it is beneficial to trade off exploitation versus exploration by measuring the element and degree of surprise associated with the immediate past observation. We devise a surprisereacting policy using two existing surprise metrics, known as the Shannon surprise and Bayesian surprise. Our analysis shows that the surprise-reacti...
European Journal of Medical and Health Sciences, 2019
Bangladesh is a small South-Asian country at the threshold of an amazing opportunity. Due to the ... more Bangladesh is a small South-Asian country at the threshold of an amazing opportunity. Due to the relatively young age of the population, there is a tremendous possibility of economic development. However, this euphoria of demographic dividend often masks the fact that there is a time limit on this opportunity and as this population gets older, we will have a completely different age structure by 2050 with more people on the other side of 65. That will create a substantial burden on our support structure and additional budget will be needed to cater to the demands of the elderly. But if we can play our cards right, then it is possible to manage that while sustaining the development curve. But we have to act now; otherwise, it will be too late.
This study examines the role of macroeconomic uncertainty and public expenditure in determining p... more This study examines the role of macroeconomic uncertainty and public expenditure in determining private fixed investment in Pakistan. It is found that individual series are nonstationary. There is a long-run relationship between private fixed investment, public consumption expenditure, public development expenditure, and market activities. It is revealed that public development expenditure stimulates private investment, whereas public consumption expenditure is detrimental to private investment. The preferred dynamic private fixed investment function confirms that in the short run, public development expenditure enhances private investment. Moreover, macroeconomic instability and uncertainty depresses private investment in Pakistan.
Abstract At low temperatures the proton magnetic resonance signals of coordinated acetonitrile in... more Abstract At low temperatures the proton magnetic resonance signals of coordinated acetonitrile in the solutions of some group (III) and group (V) representative element halides and of Ga +3 ion can be distinguished from those of bulk acetonitrile. From the relative intensities of these signals the solvation numbers of the metal halides and Ga +3 ion were determined. Reduction in the solvation number of some complexes from the expected value was observed and is explained in terms of contact ion-pair formation. The spectrum of Ga +3 ion solution contains two distinctive signals for coordinated acetonitrile. The relative intensities of these signals vary with temperature but are independent of concentration. This is explained in terms of an equilibrium between two kinetically distinguishable solvated Ga +3 species. From the temperature dependence of the proton relaxation rates the solvent exchange parameters k 1 , δH DG and δS ‡ were calculated for various systems. Variations in the kinetic parameters among the different complexes are discussed in terms of the structure of the complex and the effect of anion participation in the coordination sphere of the complex.
IEEE Journal on Selected Areas in Communications, 2016
This paper studies stochastic power control problems over a fading channel, where the transmitter... more This paper studies stochastic power control problems over a fading channel, where the transmitter randomly harvests renewable energies from environment and stores them in a battery for future data transmissions. Moreover, data packets are assumed to arrive at the data queue of transmitter with constant rate μ. To incorporate delay quality-of-service guarantees, two delay constraint models are separately considered, namely average delay model with maximum average delay constraint and statistical delay model with maximum delay outage probability constraint. Under each delay constraint model, the stochastic power control problem aims at maximizing μ considering the randomness of channel fading and energy harvesting (EH) processes. The resulting optimization problems can be formulated as infinite-horizon Markov decision processes. Under average delay model, the optimal power control policy needs to keep track of current data queue-length state in addition to the battery state. On the other hand, under statistical delay model, a sufficiently large queue-length region is assumed, hence, the optimal policy does not depend on the data queue-length state. We study various structural properties of the optimal control policies and develop online power control algorithms that converge to the optimal solutions without requiring statistical knowledge of channel fading and EH processes. By defining and learning the so-called post-decision state-value functions, the proposed learning algorithms require less complexity and converge faster than the conventional reinforcement learning algorithms. Numerical results demonstrate the effectiveness of the online learning algorithms for different delay constraint models and EH settings.
Journal of Ayub Medical College, Abbottabad : JAMC
The mandibular foramen is of particular importance to the dentist and dental specialist as it mar... more The mandibular foramen is of particular importance to the dentist and dental specialist as it marks the beginning of the mandibular canal, which transmits inferior alveolar nerve and vessels. The aim of this study was the localization of anteroposterior and superioinferior position of the mandibular foramen on the panoramic radiographs in adolescent and young adult in a selected sample of Pakistani population. This cross Sectional study was conducted in the Orthodontic department of Dr Ishrat ul ebad khan institute of oral health science, Dow University Karachi. Material comprised 150 panoramic radiographs. The radiographs were traced on a cellophane sheet. Landmarks were marked and measurements from the centre of the mandibular foramen to other landmarks were recorded. All measurements were recorded to the nearest millimetre. The mandibular foramen occupies the posterior portion of middle third on antero-posterior width of mandible. A ratio between the sides of one or almost one in...
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Papers by Imtiaz Ahmed