Sharif Digital Repository

In this study, a numerical finite difference model of self-boring pressuremeter test (SBPM) is performed. Limit pressure is believed to be a key parameter for estimation of soil parameters from pressuremeter tests, however; self-boring pressuremeter tests are practically conducted up to 10-15% strains, so determination of limit pressure usually needs extrapolation. For an alternative solution, it is recommended to consider cavity pressure corresponding to 10% strain (P10) for interpretation of soil parameters instead of limit pressure; therefore, more than 5000 numerical analyses of SBPM are carried out to correlate cavity pressure corresponding to 10% strain (P10) to sand parameters with... 

This project is a new pressure model for propagating pressure inside one or several tissues at the time of treatment with high intensity focus ultrasound (HIFU). Pressure's changes are converted to heat's changes in tissue and this is done oscillatory. When the treatment is done in deeper tissues, obtained heat can affect surficial tissues. This pressure effect also can enter surficial tissues. Amount of pressure and heat possible injury can be controlled and reduced through this mechanical modelling. In this model we have used three layers and pressure also is obtained within these three layers and is investigated averagely. Obtained tissue in this mood is kidney tissue and it is tried to... 

In real world social networks, there are multiple cascades which are rarely independent. They usually compete or cooperate with each other. Motivated by the reinforcement theory in sociology we leverage the fact that adoption of a user to any behavior is modeled by the aggregation of behaviors of its neighbors. We use a multidimensional marked Hawkes process to model users product adoption and consequently spread of cascades in social networks. The resulting inference problem is proved to be convex and is solved in parallel by using the barrier method. The advantage of the proposed model is twofold; it models correlated cascades and also learns the latent diffusion network. Experimental... 

We study the problem of fair division of a heterogeneous resource among strategic players. Given a divisible heterogeneous cake, we wish to divide the cake among n players in a way that meets the following criteria: (I) every player (weakly) prefers his allocated cake to any other player's share (such notion is known as envy-freeness), (II) the mechanism is strategy-proof (truthful), and (III) the number of cuts made on the cake is minimal. We provide methods, namely expansion process and expansion process with unlocking, for dividing the cake under different assumptions on the valuation functions of the players. Copyright © 2017, Association for the Advancement of Artificial Intelligence... 

Asphaltene deposition in the early stage of the oil reservoir life and later during any stimulation process emerges critical problems to the petroleum industry. Deposition of asphaltene aggregates raises strict problems in industries and demands markedly a practical and scientific knowledge of the mechanisms of aggregation and precipitation. Fluorescence emission spectroscopy has been widely used to illuminate the fundamental properties of crude oils and asphaltenes. It proposes analysis of some details of equilibrium, dynamic behavior, and aggregation composition of crude oil under specific condition. In this work, the fluorescence spectra of crude-oil extracted asphaltene samples were... 

A reaction of dithiocarbamic acid salts with carbonyl compounds was investigated for the first time in the presence of BF 3•OEt 2. The reaction is temperature dependent and gives gem-bis(dithiocarbamates) at 35-45 °C as a molecule with high equivalents of dithiocarbamate groups. At lower temperatures (15-20 °C), the 2-iminium-1,3-dithietane is obtained as the only product. The structure of a 2-iminium-1,3-dithietane was accomplished by X-ray crystallographic analysis  

The single stranded DNA can be adsorbed on the negatively charged surface of gold nanoparticles (AuNPs), but the rigid structure of double stranded DNA prevents it from adsorption. Signal of a tagged single stranded DNA will be quenched by the plasmon effect of the AuNP surface after its adsorption. This phenomenon has been used to study the DNA hybridization and interactions of two complementary 21mer oligonucleotides each tagged with a different fluorescent dye in the presence of 13 nm gold nanoparticles. The DNA strands used in this study belong to the genome of HIV. The obtained rank deficient three-way fluorescence data sets were resolved by both PARAFAC and restricted Tucker3 models.... 

The bale packings that are used as catalyst containing packings in reactive distillation columns are made and geometrically characterized. Pressure drop and holdup values are measured in a 10.4 cm i.d. glass column packed with bales using an air/water system. The arrangement of the bales in the bed is similar to that of industrial columns. The obtained data are used for evaluating the Stichlmair and the Eckert pressure drop models. Neither of these two models could fit the data properly. When a slight modification is made in the Eckert model, a specific model which fits the data well is prepared. This model also accounts for the effect of geometrical characteristics of the packed bed on... 

pH control is known to be a challenging problem due to its highly nonlinear nature. Several control strategies are proposed for controlling pH processes among which is the strong acid equivalent scheme. Although this technique is robust to modeling error, the controller performance is degraded if the titration curve undergoes large changes. To overcome this problem, two control schemes that are based on the strong acid equivalent strategy and that use the multiple models, switching, and tuning approach are proposed in this work. For modeling, both fixed and adaptive models are considered. An experimental setup is used to evaluate the performance of the proposed scheme. The effectiveness of... 

Gesture and motion recognition are needed for a variety of applications. The use of human hand motions as a natural interface tool has motivated researchers to conduct research in the modeling, analysis and recognition of various hand movements. In this work, we introduce a 3-D hand motion recognition. We use 3-D landmarked points on finger tips and joints followed by a HMM (Hidden Markov Model) to recognize hand motions. Experimentally, in an effort to evaluate the formation of hand gestures similar to those used in rehabilitation sessions, we studied three hand motions. Using natural hand motion features in an uncontrolled environment, we were able to classify, differentiate and quantify... 

Planning as satisfiability is known as an efficient approach to deal with many types of planning problems. However, this approach has not been competitive with the state-space based methods in temporal planning. This paper describes ITSAT as an efficient SAT-based (satisfiability based) temporal planner capable of temporally expressive planning. The novelty of ITSAT lies in the way it handles temporal constraints of given problems without getting involved in the difficulties of introducing continuous variables into the corresponding satisfiability problems. We also show how, as in SAT-based classical planning, carefully devised preprocessing and encoding schemata can considerably improve the... 

In Spatial Voting Theory, distortion is a measure of how good the winner is. It has been proved that no deterministic voting mechanism can guarantee a distortion better than 3, even for simple metrics such as a line. In this study, we wish to answer the following question: How does the distortion value change if we allow less motivated agents to abstain from the election? We consider an election with two candidates and suggest an abstention model, which is a general form of the abstention model proposed by Kirchgässner. Our results characterize the distortion value and provide a rather complete picture of the model. ©2021 AI Access Foundation  

In an experimental study, investigation is performed based on the surface-mounted hot-film sensors and surface pressure and rake pressure measurements. The boundary-layer (BL) events such as laminar separation (LS), transition onsets, and variations of the wall shear stress are discussed and compared for both pitching and plunging oscillations for various cases of before, within, and beyond the static stall angle of attack (AOA) conditions. All experiments are conducted in a low-speed wind tunnel. The surface pressures are measured using differential pressure sensors with a range from 0.075 to 1.0 psi and with a maximum error of 0.15% of their full span. In addition, the wake profile behind... 

In an experimental study, investigation is performed based on the surface-mounted hot-film sensors and surface pressure and rake pressure measurements. The boundary-layer (BL) events such as laminar separation (LS), transition onsets, and variations of the wall shear stress are discussed and compared for both pitching and plunging oscillations for various cases of before, within, and beyond the static stall angle of attack (AOA) conditions. All experiments are conducted in a low-speed wind tunnel. The surface pressures are measured using differential pressure sensors with a range from 0.075 to 1.0 psi and with a maximum error of 0.15% of their full span. In addition, the wake profile behind... 

A series of wind-tunnel tests were conducted on a Y-shaped diverterless supersonic inlet (DSI) in order to investigate its performance at various operating conditions. The present DSI was designed for a freestream Mach number of M∞ 1.65. The experiments were performed at supercritical, critical, and subcritical operating conditions and at 0 deg angle of attack and angle of side slip. The results showed that the present DSI had an acceptable performance at its design condition. A symmetric supersonic flow pattern was observed at both supercritical and critical operating conditions. At low subcritical operating conditions, the supersonic flow pattern remained symmetric too. However, at high... 

The perovskite oxide BaTiO3, doped with Ge oxides oxidized methane to C2 coupled hydrocarbons. The ultraviolet-visible spectra of pure barium titanate and Ge doped BaTi(1-x)GexO3(x=0.05,0.1) were compared. The pure barium titanate exhibited an ultraviolet absorption effect. The addition of GeO2 resulted in an increase in absorption of wavelength. Therefore, small amount of Ge decreased band gap energy. Oxygen is inserted by nucleophilic attack which may be considered as an acid-base process. For promoted BaTiO3catalysts with stable cation valance, electron donation ability of lattice oxygen is parallels to its ability of adsorb and active oxygen, and decrease the chance of deep oxidation of... 

In this mini-review, we summarize fabrication methods, formation mechanisms, factors that control the characteristics, and applications of self-assembled nanopillars. Nanopillars prepared both in the gas phase and in solutions are discussed. © 2017 Hai-Feng Ji, et al  

In natural gas pressure boosting stations, air coolers are used to reduce the gas temperature. Pressure drop as an essential factor in determining the energy performance of any pressure boosting station has a significant impact on the overall performance of the gas transmission. In this paper, a laboratory pilot is designed to investigate the effect of pressure drop reduction on the use of heating pipes at the air coolers. In addition, as a case for a gas pressure boosting station, its impact over energy performance index and pressure drop parameter has been calculated through simulating. The results show, implemented PHP tubes in an air cooler, lead to reduce tube length and improve... 

Many existing buildings are irregular in plan or elevation because of asymmetric placement of masonry infills. The stiffness of masonry infill is a considerable value relating to that of the structure. Produced torsion from eccentricity because of infill stiffness leads to extra forces and deformations in structural members and diaphragms. An appropriate alternative to solve this problem especially in existing buildings is using dampers. Dampers can enhance structural performance by reducing seismically induced lateral displacements and by reducing inelastic behavior of beams and columns. In this paper some simple models are used to show structural modeling and a conceptual discussion is... 

Effect of openings' dimensions on the relative flexural behavior of adjacent piers (independent or conjugate) in perforated shear walls is addressed. 384 designed models were made and exposed to lateral loads. For middle openings, in addition to the alpha parameter in the literature, the relative flexural behavior of piers in medium-rise buildings can be predicted as function of thickness-to-length ratio of the coupling beam and the ratio of the coupling beam length to the pier length; but in high-rise buildings, it is always conjugate. For corner openings, the alpha parameter must be modified with respect to the number of stories