Purpose: Application of heavy forces to maxillary dentition during treatment with headgear, induces high concentration of stresses in periodontal tissue. Quantification of this stress is of great concern in orthodontics. This study was designed to investigate the quantity and quality of stress response in the PDL of maxillary first molar which was subjected to high pull headgear traction using Finite Element method.Methods and Material: In an experimental study, a three-dimensional finite element model of maxillary dentition, consisting of 17096 elements and 23013 nodes, was developed based on a young human skull. The forces were applied to the maxillary first molar in the stabilized Arch by means of a rectangular full size arch wire in (022) slot bracket. Mechanical properties of this model were based on previous studies. A 350 gram force was used for high pull headgear to affect the dentition (+30 degree) and stress distribution was investigated in buccal, palatal, mesial and distal side and in cervical, middle, apical sections of the PDL. The quantity of stresses were expressed as principal stresses (1,2,3), while the negative and positive signs indicated compressive and tensile stresses.Results: The buccal surface of PDL of mesiobuccal root and the buccal, palatal and distal surface in cervical region of PDL of distobuccal root and the distal surface of the PDL of palatal root had received a great deal of stresses, in addition, the over all stress distribution in roots of molar had intrusive nature.Conclusion: The extension of high stress concentration areas observed after using high pull headgear is limited to some root surfaces specially the distobuccal root.

One of the obvious reasons for most disorders in network service provisioning is network path congestion. Congestion avoidance in today's networks is too costly and sometimes impossible. With the introduction of SDN, centralizing the equipment's control plane has become possible. This paper presents an enhanced method named ESV-DBRA to avoid congestion in multi-tenant SDN networks. At first, ESV-DBRA monitors the traffic load and delay of all network paths for each tenant individually. Then, by merging the parameters obtained from the monitoring, the Service Level Agreements (SLA), and a novel proposed cost function, it calculates the cost of the network paths per tenant. As a result, traffic for each tenant is routed through the path/paths at the lowest possible cost from the tenant's perspective. Next, the bandwidth quotas will be calculated and assigned to the tenants over their optimal routes. Afterward, whenever congestion is likely to occur in a path, ESV-DBRA automatically changes the route or bandwidth of the tenants' traffic related to this path to avoid congestion. Related algorithms are also proposed.Eventually, simulations show that the proposed method effectively increases bandwidth utilization by 10.76%.

Different types of contact, including contact between node pairs, any-contact of nodes, and contacts of the entire network, are used to characterize social relations in mobile social networks. Different modes of routing, from the point of view of message delivery semantics, encompass unicasting, multicasting, any-casting, and broadcasting. Studies have shown that using probability distribution functions of contact data, which is mainly assumed to be homogeneous for nodes, improves the performance of these networks. However, there exists an important challenge in studies on distributions. A lot of works apply the distribution of one type of contact to other types. Hence in routing applications, it causes to use of the distribution of one type of contact for any mode of routing. This study provides a complete solution to model each type of homogeneous contact data distribution and to use them in different modes of routing. We propose a routing algorithm that uses this new model. Results show that our solution improves the average latency of comparing methods Epidemic, TCCB, and DR about 3.5-times, 30%, and 45%, respectively. It achieves a delivery rate of about 5% and 6%, and average latency about 6% and 8% better than that of DR and TCCB, respectively.

Monitoring and evaluation of transformers are essential to prevent their insulation failure. In this paper, the use of 2-furan-carboxaldehyde (2-FAL) and methanol (MeOH) concentrations as the main products of paper insulation degradation, and insulation condition markers, has been studied. In order to study the degradation process and production of degradation products, the thermal aging process of the transformer insulation system was implemented in laboratory conditions. The results of laboratory studies show that in the early stages of degradation the amount of MeOH is significant compared to 2-FAL. Also, the estimation of the degree of polymerization (DP) in the early stages of degradation (DP>800) through MeOH concentration and with decreasing DP (DP <800) through 2-FAL concentration is closer to the real value. The results of studies performed on 35 distribution transformers confirm the production of significant amounts of MeOH in the early stages of degradation. Also, the estimated DP values for the studied transformers were obtained through 2-FAL and MeOH concentration. The results show that estimating the amount of DP through MeOH concentration is associated with a probability of error of about 9% compared to estimating DP through 2-FAL concentration.

In this paper, a review of stress distribution in circular tunnels is presented. Given that there are many different theories and methods on how to distribute stress around the tunnel, some of which are challenging. This led to a more accurate comparison. The research method in this article is based on reviewing and comparing conventional methods in the articles of researchers in this field. The results of this research are shown in comparative tables of different methods. In general, in the rocky and soil masses in the depths of the ground, stresses called in situ stresses act. The main cause of in situ stresses is the weight of the upper classes and the tectonic activities of the region. Understanding the status of inductive and inductive stresses is one of the essential requirements of tunnel design and other underground structures because in many cases the inductive stresses may exceed the rock resistance level and, if not thought through, may damage the structure. This perturbation of the in situ stress condition only extends to a certain distance from the tunnel axis, which is called the radius of impact, and beyond that, the stress situation remains intact. In addition to the shape and dimensions of the tunnel, the manner and velocity of tunnel digging as well as the staging of the various sections (in cases where tunnel sections are dug in several steps) are also effective in arranging the induced stresses and the drilling system must be designed to minimize instability.

This paper presents the coating thickness effect on the stress distribution of a coated cylinder head. A typical thermal barrier coating was applied on a diesel engine cylinder head. Thus, the residual stress which occurred during the plasma thermal spraying was also considered. The coating system consisted of two layers; a metallic bond coat and a ceramic top coat. The bond coat thickness is considered as 50 to 250 µm and the top coat thickness was considered as 200 to 800 µm. The stress distribution was found by the finite element analysis using the ABAQUS software. Then, stress distributions were compared for various coating thicknesses. Finally, optimized values for each layer are suggested.

Background: The most frequently used test for evaluation of fetal health is the Non Stress Test (NST). Unfortunately it has a high incidence of false positive results. The combination of vibroacoustic stimulation with the NTS has been shown to reduce non reactive results.Methods: A tests assessment method was chosen with a simple randomized sampling. 40 pregnant women with non reactive NST in the first 20 minutes who received VAS in one of Tehran University's Hospitals were compared with BPP scores. A vibroacoustic stimulation was applied for a 3 seconds on the maternal abdomen and fallowed within 10 minutes. Data collection tools were NST, sonography instruments, NST result paper, tooth brusher, watch, demographic questioner and check list. Data analysis was made by descriptive static and by using the Fisher's Exact Test (with level of significant at p<0/05). All statistical analysis were performed using an spss/win.Results: After VAS, 70% of non reactive tracing became reactive. All cases with fetal reactivity response after a VAS had a subsequent BPP score of 8 (negative predictive value of 100%). False positivity of VAS was lower than NST.Conclusion: VAS offers benefits, by decreasing the incidence of non reactive test and reducing test time. VAS lowers the rate of false positive NST. VAS is safe and allows more efficient of prenatal services. This test could be used as a rapid antepartum test to predict fetal well-being.

A powerful method for analysis of stress and deformation around underground structures is the analytical method. Among the analytical models the one that utilizes complex potential functions for the solution have the advantages of applicability and accuracy. Most of the governing solutions are applied to the circular shape tunnels or simple cross-section tunnels with one- or two dimensional in-situ normal stresses conditions. For the elliptical shape tunnels, there are three methods of solution based on the complex potential analysis. They are Stevenson method, Mushkelishvilli method, and Series method for approximation of the complex potential functions. In the above models, the solutions are not unique in details, but all satisfy the boundary conditions on the tunnel surface and far field stress situation. The interested readers to these analytical methods' solutions to tunnels with different shapes can refer to the papers and books governing Timoshenko and Goodier, Savin, and Muskhelishvilli. In the above models, the Stevenson one is a powerful and robust model for analysis of stress and deformation on and around the elliptical tunnels. Therefore, in this research, the complex potential and conformal mapping functions of Stevenson model are applied to obtaining the stress around those openings. The analysis is a two-dimensional plane stress or plane strain conditions. Therefore, the solution can be used for stress concentration around long tunnels. The parameters of the governing complex potential functions are obtained by satisfying the boundary conditions and the problem hypothesis. Then by applying the sequence differentiations of the potential and conformal complex functions to the formulation the normal and shear stresses around the tunnel are calculated. The stress field, which is considered around tunnel, is uniaxial and biaxial compressive stresses. The results from three solved problems show the similarity between the calculated stresses on the tunnel surface with the Muskhelishvilli model. The solution can also be used for the situation of in-situ shear stress boundary condition around tunnel. It is suggested that the formulation be developed for the deformations on the surface and around the elliptic tunnels.