Sharif Digital Repository

Data aggregation is a very important method to conserve energy by eliminating the inherent redundancy of raw data in dense WSNs. Although structured approaches are particularly useful for data gathering applications, they incur high maintenance overhead in dynamic scenarios for event-based applications. Moreover, a WSN should be capable of timely fulfilling its mission without losing important information in event-critical applications. In this paper, we focus on designing a structure-free Real-time data AGgregation protocol, RAG, using two mechanisms for temporal and spatial convergence of packets - Judiciously Waiting policy and Real-time Data-aware Anycasting policy. Using extensive... 

In this work, solvent blending in combination with extruding are applied to provide polystyrene/silica nanocomposite specimens. Transmission electron microscope (TEM) and scanning electron microscope (SEM) show same nanoparticle dispersion in PS matrix in low to high filler loadings. Differential scanning calorimetry (DSC), dynamic mechanical thermal analyzer (DMTA) and thermogravimetric analyzer (TGA) were used to study the thermophysical characteristic of the nanocomposites in solid state. In addition, the melt state rheological behavior of the samples was investigated under constant and zero shear rates. Interestingly, different behaviors were detected in nanocomposites in low and high... 

A very efficient and mild procedure for the trimethylsilylation of a wide variety of alcohols, including primary, allylic, benzylic, secondary, hindered secondary, tertiary, and phenols with hexamethyldisilazane on the surface of silica gel dispersed with LiClO4 in room temperature at few minutes in excellent yields under neutral conditions is reported. This procedure also allows the excellent selectivity under LP-SiO2 system for silylation of alcohols in the presence of amine and phenolic hydroxy groups  

Assessment and planning of crisis management with the natural disasters approach include many components. In this regard, floods and earthquakes are some of the fundamental pillars in this field. With this view, paying attention to the current and future planning and research priorities of the world shows that crisis management in flood-prone and earthquake-prone areas and increasing resilience are the most important priorities for sustainable development studies and planning in the world. The western region of Iran (Lorestan province) has a special place due to the prominent features of flood and seismicity. This study aims to investigate the current situation regarding floods and... 

Endoscopic capsule robots (ECRs) have introduced feasible and painless gastrointestinal diagnostics to endoscopic procedures. To further enhance the capability of these revolutionary devices, many research groups have attempted to equip ECRs with functions such as active locomotion, drug delivery, and biopsy. This study addresses the challenges related to the biopsy functionality of ECRs by introducing a remote biopsy mechanism adapted from the magnetic spring concept. The mechanism consists of one axial permanent magnet (PM) fixed inside the ECR's body, a radial PM free to translate along the device length and rotate perpendicular to its magnetization direction, and conventional biopsy... 

Autonomous robotic grasping has emerged as a valuable capability for automating everyday household tasks like table setting (bossing), cleaning, and meal preparation. Still, accurately detecting and manipulating diverse everyday objects in unstructured home environments remains a significant challenge. In this study, an integrated robotic system combining YOLOv8s-seg deep learning for object detection and segmentation with computer vision techniques to determine optimal grasping points is proposed. The accuracy of this model has also been compared with other models through their mAP0.5, mAP.05-.95, precision and recall. A custom dataset of over 1000 images containing common household objects... 

In recent years, extensive experiments have shown that classical continuum theory cannot predict the behavior of mechanical microstructures with small size. To accurately design and analyze micro- and nano-electro-mechanical systems, size-dependent continuum theories should be used. These theories model micro- and nano-electro-mechanical systems with higher accuracy because they include size-dependent parameters. In this paper, polysilicon nano-beam is modeled using modified couple stress and Eringen's nonlocal elasticity theories. First, partial differential equations governing the vibration of nano-beams are converted to a one D.O.F. differential equations using Galerkin method, resulting... 

In this study, dynamic response of a micro- and nanobeams under electrostatic actuation is investigated using strain gradient theory. To solve the governing sixth-order partial differential equation, mode shapes and natural frequencies of beam using Euler–Bernoulli and strain gradient theories are derived and then compared with classical theory. Galerkin projection is utilized to convert the partial differential equation to ordinary differential equations representing the system mode shapes. Accuracy of proposed one degree of freedom model is verified by comparing the dynamic response of the electrostatically actuated micro-beam with analogue equation and differential quadrature methods.... 

Deep excavation in urban areas can cause instability problems due to significant settlement at the ground surface and large movements at the excavation facing walls. One of the most popular methods used to stabilise these excavations is utilising soil-nailing method. This method has also been widely used to stabilise natural slopes and earth retaining structures. Because of the complexity involved in the mechanism of this stabilising system due to interacting effects of the soil, nails, grout and shotcrete, numerical modelling with high accuracy should be used to analyse the behaviour of the soil-nailed walls. Considering all aspects of soil-structure interaction in the present research, a... 

Deep excavation in urban areas can cause instability problems due to significant settlement at the ground surface and large movements at the excavation facing walls. One of the most popular methods used to stabilise these excavations is utilising soil-nailing method. This method has also been widely used to stabilise natural slopes and earth retaining structures. Because of the complexity involved in the mechanism of this stabilising system due to interacting effects of the soil, nails, grout and shotcrete, numerical modelling with high accuracy should be used to analyse the behaviour of the soil-nailed walls. Considering all aspects of soil-structure interaction in the present research, a... 

Deep excavation in urban areas can cause instability problems due to significant settlement at the ground surface and large movements at the excavation facing walls. One of the most popular methods used to stabilise these excavations is utilising soil-nailing method. This method has also been widely used to stabilise natural slopes and earth retaining structures. Because of the complexity involved in the mechanism of this stabilising system due to interacting effects of the soil, nails, grout and shotcrete, numerical modelling with high accuracy should be used to analyse the behaviour of the soil-nailed walls. Considering all aspects of soil-structure interaction in the present research, a... 

Anchored wall system is one of the common methods used for deep excavation stabilization adjacent to sensitive structures in urban areas. A key aspect of the stability analysis of deep excavations is the amount of deformations occurring on the facing wall and the adjacent structures. In this research, a large number of parametric studies considering all aspects of soil-structure interaction is carried out for different excavation geometries to find the optimal design, and the outcome is shown in the form of design tables and charts. Also, by a GA-PSO algorithm and using the large database obtained from the numerical simulations, a simple equation is developed that can predict the deflections... 

The significance of aromatic amines as crude substances in diverse applications has attracted extensive consideration in the field of economic procedures for the reduction of nitroarenes. Also, the formation of Carbon–Carbon bond as a dominant step in the structure of complex molecules is an important phenomenon in chemical reactions. Improvements of eco-friendly methodologies for reduction process and Carbon–Carbon bond formation have been noticeable. The present work represents through a capable heterogeneous Pd catalyst, the reduction of nitroarenes to the corresponding amines in the presence of N2H4 as a weak hydrogen donor reagent in the room temperature and solvent-free condition was... 

The current paper deals with the energy generation system utilizing three kinds of renewable energy solar, ocean thermal, and wind energy with climatic circumstances near regions with higher potential for the ocean thermal energy conversion system with suitable conditions based on solar radiation and wind speed as a source of energy. The suggested system is evaluated using a beach welfare complex based on the total daily electricity. The system’s main components included a Rankine organic cycle, turbine, pump, thermoelectric, a flat plate solar collector, heat exchanger, and wind turbine. EES software was utilized to simulate the system and acquire thermodynamic results. For areas with good... 

While import taxes are easier to levy, there is increasingly more evidence that importers engage in trade tax evasion. The literature uses, trade gap, the difference between reports from the two ends of a trade link, as a proxy for illegal imports. Many papers have found a robust positive correlation between import tax rates and the trade gap. However, like any other tax, importers could avoid paying import duties through legal provisions. Such opportunities are abundant in Iran and could impose a downward bias on the evasion elasticity estimates. Using disaggregated trade reports from 21 partners and Iran Customs Administration from 2004 to 2013, we show three results. First, a... 

This article is focused on a simple approach for determining the natural frequency and mode shape of laminated angle-ply plates with various shapes by rectangular orthotropy. Since the boundary of the domain for all shapes are not natural to the material coordinate axes it seems appropriate to express the plate displacement amplitude in terms of a polynomial and a general shape function multiplication in the x and y coordinates. The boundary conditions considered are clamped and simply supported edges. The effect of the fiber orientation, layer number, and lamination sequence on the natural frequencies of plates is also considered. The natural frequency determinant has been generated using... 

Lifetime is the most important concern in wireless sensor networks due to limited battery power of sensor nodes. In this paper, we focus on designing an energy-efficient and energy-aware routing algorithm, LLR, to increase the operational lifetime of multi-hop wireless sensor networks in the presence of unreliable communication links. Our proposed protocol utilizes a parameter, Broadcasting Delay, in each node associated with the hop parameters passed by a route request packet to select long lifetime paths in the network. The key point in Broadcasting Delay formulation is that it includes both node and link specific parameters. We use two different scenarios: either the link layer... 

The present study reports synthesis of BaFe12O19 nanoparticles by sol gel technique followed by its characterization using Energy dispersive X-ray spectroscopy (EDS), X-Ray diffraction (XRD), field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM) analysis, and Fourier-transform infrared spectroscopy (FTIR). The BaFe12O19 nanoparticles have been applied to construct a modified graphite screen-printed electrode (GSPE). BaFe12O19/GSPE has been applied as a working electrode in the analysis of tramadol and acetaminophen by voltammetric techniques. The BaFe12O19/GSPE showed a good selectiveness for analysis of tramadol in the presence of acetaminophen with the... 

Morphine is a strong opioid used for the treatment of moderate to severe pain. Its use is, however, associated with adverse effects including sedation, nausea, constipation, respiratory depression, and development of tolerance as well as dependence. Thus, in this work electrochemical oxidation of morphine has been done on BaFe12O19 nanoparticles of the modified electrode. BaFe12O19 nanoparticles of the modified graphite screen-printed electrode (GSPE) and the bare GSPE were compared, representing that the modified electrode takes advantages of higher sensitivities and selectivities with lower limit of detection. Differential pulse voltammetric procedure has been used to analyze data. Results... 

Different nonlinearities in micro-electro-mechanical resonators lead to various nonlinear behaviors such as chaotic motion which can affect the resonator performance. As a result, it is important to properly identify and analyze the chaotic regions in resonators. In this paper, a novel method is proposed for prediction of the chaos in the micro- and nano-electro-mechanical resonators. Based on the proposed method, first an accurate analytical solution for the dynamics behavior of the nano-resonators is derived using the multiple scales method up to the second order. The results obtained by this analytical solution are validated by comparing them with the numerical ones. Using the analytical...