Sharif Digital Repository

This research examines the impacts of climate change and socio-economic variables on the hydrological cycle, reservoir water management, and hydropower capacity at the Gezhouba Dam. The Gezhouba Dam serves as a crucial hydroelectric power station and dam, playing a vital role in regulating river flow and generating electricity. In this study, an innovative method is employed, combining the Soil and Water Assessment Tool (SWAT), Support Vector Regression (SVR), and Long Short-Term Memory (LSTM) models. This model is optimized using the Developed Thermal Exchange Optimizer. This optimized combined model significantly enhances the reliability and precision of the forecasting inflow and... 

Bio-composites are outstanding alternatives to prevalent biomaterials in medical instruments due to their supreme material properties. On the other hand, mechanical analyses of bio-systems should be carried out to optimize the designed biomedical applications such as medical implants. Therefore, bulk wave propagation analysis of functionally graded (FG) bio-composite beams could serve as design targets of biomedical structures. Some applications like medical implants have a layered structure and FG composites will be an appropriate choice for constitutive material of such structures. In the current study, the influence of imperfection on the propagation of bulk waves in FG bio-composite... 

Detrimental impacts of dust caused by mine tailings have yielded to several studies on the efficiency of different soil stabilizers. Bacterial stabilization has been recognized as a reality within recent decades, where bacteria could get adhesion to the grains and stabilize the soil particles. However, these bacteria are prone to be destroyed while exposed to the normal environmental conditions. In this study, the effects of microcapsules containing two types of bacterial freeze-dried spores (B.Subtilis Natto LMG 19457 and B.ESH) have been investigated on the mine tailing stability in terms of two parts. The first part of the study is dedicated to the fabrication of microcapsules within the... 

In this paper, we propose a general delay and stability performance analysis in Heterogeneous Cellular Caching Networks (HCCNs), based on queuing theory. We introduce new performance metrics in HCCNs and propose an optimization problem which minimizes the average experienced delay for users by ensuring the stability of the network. In addition, from the design perspective, we address the problem of finding the minimum cache size for the small cell base stations (SBSs) for having a tolerable average delay and also a stable network. Finally, the analytic expressions derived in this paper are validated through real trace-driven experiments on traffic of YouTube video requests  

Caching at network edges has attracted more and more research interests recently for the purpose of alleviating the network traffic pressure especially in backhaul links and improving user experience. We study Heterogeneous Cellular Caching Networks (HCCNs) consisting of macro cells in which N small cell base stations (SBSs) equipped with cache memory operate in conjunction with the macro cell base station (MBS). We provide closed-form expressions of the MBS and SBSs utilization factors and average user-experienced-delay in HCCNs with overlapping coverage regions, considering general traffic models for the request arrivals based on the Independent Reference Model (IRM) and renewal traffic... 

Caching at network edges has attracted more and more research interests recently for the purpose of alleviating the network traffic pressure especially in backhaul links and improving user experience. We study Heterogeneous Cellular Caching Networks (HCCNs) consisting of macro cells in which $N$ small cell base stations (SBSs) equipped with cache memory operate in conjunction with the macro cell base station (MBS). We provide closed-form expressions of the MBS and SBSs utilization factors and average user-experienced-delay in HCCNs with overlapping coverage regions, considering general traffic models for the request arrivals based on the Independent Reference Model (IRM) and renewal traffic... 

The IEEE 802.11 contention-based distributed coordination function has been used in ad hoc networks, and so far, a comprehensive mathematical analysis of such multihop systems has not been reported in the literature due to complicating factors such as hidden terminals and the unreachability problem. In this paper, we propose a new analytical model based on the parallel space-time Markov chain for IEEE 802.11 medium access control (MAC) in multihop ad hoc networks. The proposed scheme is able to model the hidden-terminal and unreachability phenomena. Extensive evaluation is conducted to demonstrate the accuracy of the proposed framework. © 2009 IEEE  

This paper presents an experimental research for studying the relative and interactive effects of three physicochemical fluid characteristics (viscosity, pH, and ionic strength) on the incipient motion of a granular particle under laminar flow condition. Critical flow velocity for particle's incipient motion, an important factor for evaluating flow-induced soil erosion, was used to quantify the relative erosive capacity of the test fluids. Response surface methodology (RSM), a statistical design of experiments, was used to design and implement 20 test fluids with various levels of the three fluid characteristics. Incipient motion of a highly spherical glass bead positioned atop a specially... 

Many performance evaluations for the IEEE 802.11 Distributed Coordination Function (DCF) have been previously reported in the literature; most studies are based on saturation analysis, and a few models under a finite-load condition adopt an M/G/1 queuing system. However, using M/G/1 queuing only considers the first moment of the frame service time to derive the probability of the transmission queue being vacant. In this paper, we model the DCF using the parallel space-time Markov chain, where the frame arrivals are tracked by monitoring the transmission queue during transitions between successive states of the space-time Markov chain. The proposed framework provides the possibility of... 

In this paper, using the so-called Parallel Space-Time Markov Chain (PSTMC) framework we analyze the IEEE 802.11 Distributed Coordination Function (DCF) frame service time, jitter, and queuing delay in a single-hop non-saturated wireless network. PSTMC framework provides the possibility of simultaneous modeling of backoff and post-backoff procedures, in addition to the transmission queue status of a non-saturated 802.11 station. To the best of our knowledge, the presented contribution is the first analysis of service time, i.e., access delay and retransmission delay, plus queuing delay at the same time, when the precise modeling of binary exponential backoff (BEB) scheme in medium access... 

This paper assesses thermoelastic damping (TED) in circular nanoplates by incorporation of the small-scale effect into structural and thermal domains. The nonlocal elasticity theory and dual-phase-lag (DPL) heat conduction model are exploited for achieving the size-dependent coupled thermoelastic equations. By choosing time-harmonic and asymmetric form for deflection and temperature change, and solving the size-dependent thermoelastic eigenvalue problem, the damped natural frequency of circular nanoplate is extracted. On the basis of the complex frequency approach, an analytical relation, for the description of TED in circular nanoplates, is derived. For different boundary conditions and... 

This study investigates whether and how the pursuit of certain commercial business practices such as market orientation and market disruptiveness capability improves both the economic performance and social performance of social enterprises. Based on the empirical data collected from 164 UK social enterprises, our results show that market orientation improves social performance and economic performance simultaneously, whereas market disruptiveness capability improves only the economic performance, not the social performance, of social enterprises. However, we found a positive interaction effect of market disruptiveness capability and market orientation on social performance, while its effect... 

Microorganisms have been essential in the natural world for millions of years, contributing significantly to environmental interaction. It has been disoverd that some bacteria are potential in geotechnical and environmental engineering due to their outstanding ability of biomineralization. Therefore, how to train bacteria as special and professional “workers” for biomineralization is increasingly a key topic in related research fields. This article briefly introduces the methods that are commonly utilized to improve the environmental adaptability and mineralization efficiency of bacteria, including microbial domestication, microbial mutation breeding, microbial targeted screening, and... 

In this paper, the characteristics of a hybrid regenerative electromagnetic (EM) damper are first determined and experimentally examined. The main idea is to have two modes of operation for the EM damper, namely passive energy harvesting and semi-active modes. In the passive mode, the vibrational energy of an underlying structure is harvested and stored in a rechargeable battery. The harvested energy can then be employed in the semi-active control mode to supply the power demand for the required sensors and microcontroller. This hybrid damper would thus be capable of realizing the characteristics of a self-powered EM damper. A prototype of the damper was designed and tested under different... 

Purpose: This study aimed to investigate the biomechanical impact of laminectomy on cervical intersegmental motion and load sharing using a parametric patient-specific finite element (FE) model towards providing clinicians with a viable quantitative tool for informed decision-making and improved surgical planning. Methods: Ten subject-specific nonlinear osteo-ligamentous cervical spine (C3–C7) FE models were developed using X-ray image-based algorithms. The models were used to evaluate the effect of laminectomy on lower cervical spine biomechanics for two-level (C3–C4) and three-level (C3–C5) laminectomy procedures. Results: The average cervical spine ranges of motion (ROM) for the pre-op... 

Purpose: This study aimed to investigate the biomechanical impact of laminectomy on cervical intersegmental motion and load sharing using a parametric patient-specific finite element (FE) model towards providing clinicians with a viable quantitative tool for informed decision-making and improved surgical planning. Methods: Ten subject-specific nonlinear osteo-ligamentous cervical spine (C3–C7) FE models were developed using X-ray image-based algorithms. The models were used to evaluate the effect of laminectomy on lower cervical spine biomechanics for two-level (C3–C4) and three-level (C3–C5) laminectomy procedures. Results: The average cervical spine ranges of motion (ROM) for the pre-op... 

We propose the first method that realizes the Laplace mechanism exactly (i.e., a Laplace noise is added to the data) that requires only a finite amount of communication (whereas the original Laplace mechanism requires the transmission of a real number) while guaranteeing privacy against the server and database. Our mechanism can serve as a drop-in replacement for local or centralized differential privacy applications where the Laplace mechanism is used. Our mechanism is constructed using a random quantization technique. Unlike the simple and prevalent Laplace-mechanism-then-quantize approach, the quantization in our mechanism does not result in any distortion or degradation of utility.... 

Recently, an inequality satisfied by noncontextual hidden-variable models and violated by quantum mechanics for all states of a four-level system has been derived based on an information-theoretic distance approach to nonclassical correlations. In this Rapid Communication, we experimentally demonstrate the violation of this inequality with single photons. Our experiment offers a method to study a distinction between quantum and classical correlations from an information-theoretic perspective. © 2020 American Physical Society  

Understanding controls of P movement through watersheds are essential for improved landscape management in intensively managed regions. Here, we analyze observational data from 104 gaged river sites and 176 nongaged river sites within agriculturally dominated watersheds of Minnesota, USA, to understand the role of landscape features, land use practices, climate variability, and biogeochemical processes in total, dissolved and particulate P dynamics at daily to annual scales. Our analyses demonstrate that factors mediating P concentration-discharge relationships varied greatly across watersheds and included near-channel sediment sources, lake and wetland interception, assimilation by algal P,...