A Middleware for the Internet of Things

The Internet of Things (IoT) connects everyday objects including a vast array of sensors, actuators, and smart devices, referred to as things to the Internet, in an intelligent and pervasive fashion. This connectivity gives rise to the possibility of using the tracking capabilities of things to impinge on the location privacy of users. Most of the existing management and location privacy protection solutions do not consider the low-cost and low-power requirements of things, or, they do not account for the heterogeneity, scalability, or autonomy of communications supported in the IoT. Moreover, these traditional solutions do not consider the case where a user wishes to control the granularity of the disclosed information based on the context of their use (e.g. based on the time or the current location of the user). To fill this gap, a middleware, referred to as the Internet of Things Management Platform (IoT-MP) is proposed in this paper.Comment: 20 pages, International Journal of Computer Networks & Communications (IJCNC) Vol.8, No.2, March 201

Water and charge transport models in proton exchange membranes: An overview

Recently, the significant role of water management in affecting the performance and durability of proton exchange membrane fuel cell (PEMFC) has been subjective to an intensive research to understand water transport phenomena which is marked by two processes: water adsorption and water diffusion. Various mathematical models have been developed to address both processes on a different basis. This article briefly reviews various water transport models in a comparative manner to have a better understanding on the role of water hydration with respect to membrane structure and transport mechanism, in affecting the proton transport in the membranes. A discussion on the validity and reliability of the models for describing the water management is also presented. The limitations that are required to be overcome to design new materials meeting the new trends of membranes development for fuel cell are also highlighted

Removal of Hydrogen Sulfide by Physico-Biological Filtration Using Dried Activated Sludge and Rice Husk Silica

The main goal of this study was to determine the effectiveness of mixed rice husk silica with dried activated sludge as a packing material for physico-biological filter for removal of hydrogen sulphide (H2S). Removal efficiency (RE), elimination capacity (EC), and pressure drop were used to show the performance of the filters. Three separate filters (physical, biological, and physico-biological filters) were built using PVC cylinder (packed to one litter). Rice husk silica, dried activated sludge and mixture of rice husk silica with dried activated sludge were used in these physical, biological and physico-biological filters, respectively. In this study, the system was operated under different conditions of two parameters, namely different inlet gas concentration and different inlet gas flow rate. The inlet and outlet concentrations of H2S were measured using H2S detector model ppb RAE 3000, USA. In order to determine the characteristics of rice husk silica, the Brunauer-Emmett Teller (BET) specific surface area was performed using a ThermoFinnigan Sorptomatic apparatus and nitrogen adsorption at -196°C. Both the shape and pores of rice husk silica were studied using scanning electron microscope (SEM). The BET method showed that rice husk silica has a very high surface area (226.3 m2/g) with a median pore radius of 2.4 nm and a mesoporous structure. Meanwhile, the chemical composition analysis showed that rice husk silica consisted up to 97.35 % of SiO2. The physico-biological filter showed more than 99.96 % RE with empty bed residence time (EBRT) of 45 to 90 sec and 300 ppm inlet concentration of H2S. However, the RE decreased to 96.87 % with the EBRT of 30 s. In the same condition, the biological filter showed 99.37% RE. Nonetheless, the RE was shown to have dropped to 82.09 % with the EBRT of 30 s. The physical filter showed an average RE of 45.83 % with EBRT of 75 to 90 s, and it was saturated after 13 days of operating time with 300 ppm inlet concentration of H2S. The maximum EC was obtained in the physico-biological filter up to 52.32 gm-3h-1, with the RE of 96.87% and H2S mass loading rate of 54 gm-3h-1. The maximum EC in the biological filter was obtained up to 44.33 gm-3h-1 with the RE of 82.09% and the H2S mass loading rate of 54 gm-3h-1. In the physical filter, on the contrary, the maximum EC was obtained only up to 11.47 gm-3h-1 with the RE of 62.41% and the H2S mass loading rate of 18.36 gm-3h-1. After 53 days of operating time and 54 gm-3h-1 of mass loading rates, the maximum pressure drop reached to 3.0 and 8.0 (mm H2O) for the physico-biological and biological filters, respectively. Nevertheless, the pressure drop did not increase in the physical filter in the same condition. In biological and physico-biological filters, there is a direct and very high relationship between the increase of the H2S mass loading rate and the amount of pressure drop (r= 0.98, p< 0.01) and (r= 0.96, p< 0.01), respectively. Based on the findings of this study, mixed rice husk silica and dried activated sludge could be considered as suitable packing material for the physico-biological filter to remove H2S

Effect of different parameters on sonochemical synthesized nanocrystalline TiO2 particles

An ultrasonic-assisted method to directly prepare nanocrystalline TiO2 has been used. TiO2 was synthesized by the hydrolysis of Tetraisopropyl titanate (TIPT) in the presence of de-ionized water and ethanol under high-intensity ultrasonic irradiation (24 KHz, 300 W/cm2) at different conditions. The effect of water content, water-to-TIPT ratio, water-to-ethanol ratio and sonication time on the particle size of TiO2 has been investigated by using design of experiment (DOE). The water content, water-to-TIPT ratio, water-to-ethanol ratio and sonication time were varied in the range 100-150 ml, 50-75 v/v, 20-30 v/v and 3-4 hr, respectively. Particle size of TiO2 was characterized using particle size analyzer. The results of DOE show that water content has the greatest effect on the particle size of TiO2

The efficacy of prolonged speech technique in boys with mild stuttering

زمینه و هدف: لکنت زبان اختلالی حرکتی در جریان روان و پیوسته گفتار بوده که می تواند در شدت های مختلف بروز کند. بر اساس تجربیات بالینی اینگونه به نظر می رسد که پاسخ افراد دارای لکنت در گروه خفیف، متوسط و شدید به انواع شیوه های گفتار درمانی مشابه و یکسان نمی باشد. لذا هدف از این پژوهش، بررسی اثربخشی شیوه گفتار کشیده در درمان افراد دارای لکنت خفیف است. روش بررسی: در این مطالعه نیمه تجربی 44 پسر 14-8 ساله (با میانگین سنی 9/1±8/10 سال) مبتلا به لکنت خفیف از بین جمعیت دانش آموزی مدارس پسرانه شهر اهواز به روش در دسترس انتخاب شدند. در گروه مورد 30 نفر تحت 20 جلسه گفتار درمانی فشرده با شیوه گفتار کشیده قرار گرفتند. در گروه شاهد 14 نفر بدون شیوه گفتار کشیده فقط جلسات مشاوره و کتابخوانی داشتند. نمرات شدت لکنت قبل، بلافاصله و 3 ماه پس از مداخله به وسیله نسخه سوم ابزار سنجش شدت لکنت (SSI-3) تعیین شده و به کمک آزمون های آنالیز واریانس مقادیر تکراری وt مستقل، مورد تجزیه و تحلیل قرار گرفت. یافته ها: نتایج مطالعه نشان داد که در گروه مورد نمرات شدت لکنت، بلافاصله و سه ماه بعد از مداخله به طور معنی داری کمتر از گروه شاهد بود (001/0PP) در صورتی که در گروه شاهد این اختلاف مشاهده نگردید (067/0=P). نتیجه گیری: نتایج نشان داد شیوه گفتار کشیده روشی موثر و کارآمد در کاهش شدت لکنت پسران دارای لکنت خفیف بوده و همچنین ماندگاری و ثبات این شیوه درمانی در گفتار این افراد حتی تا 3 ماه پس از مداخله نیز وجود دارد

Signed star k-domatic number of a graph

Let $G$ be a simple graph without isolated vertices with vertex set $V(G)$ and edge set $E(G)$ and let $k$ be a positive integer. A function $f:E(G)\longrightarrow \{-1, 1\}$ is said to be a signed star $k$-dominating function on $G$ if $\sum_{e\in E(v)}f(e)\ge k$ for every vertex $v$ of $G$, where $E(v)=\{uv\in E(G)\mid u\in N(v)\}$. A set $\{f_1,f_2,\ldots,f_d\}$ of signed star $k$-dominating functions on $G$ with the property that $\sum_{i=1}^df_i(e)\le 1$ for each $e\in E(G)$, is called a signed star $k$-dominating family (of functions) on $G$. The maximum number of functions in a signed star $k$-dominating family on $G$ is the signed star $k$-domatic number of $G$, denoted by $d_{kSS}(G)$

An integrated approach to simulate gas turbine secondary air system

© 2023 The American Society of Mechanical Engineers. All rights reserved.One of the most critical parts of a modern gas turbine that its reliability and performance has a great influence on cycle efficiency is the secondary air system (SAS). Modern systems functions to supply not only cooling air flow for turbine blades and vanes but sealing flow for bearing chambers and turbine segments as well as turbine disk s' purge flow in order to eliminate hot gas ingestion. Due to the various interactions between SAS and main gas, consideration of the former is substantially crucial in design and analysis of the whole engine. Geometrical complexities and centrifugal effects of rotating blades and disks, however, make the flow field and heat transfer of the problem so complicated AND too computationally costly to be simulated utilizing full 3-D CFD methods. Therefore, developing 1-D and 0-D tools applying network methods are of great interests. The present article describes a modular SAS analysis tool that is consisted of a network of elements and nodes. Each flow branch of a whole engine SAS network is substituted with an element and then, various branches (elements) intersect with each other just at their end nodes. These elements which might include some typical components such as labyrinth seals, orifices, stationary/rotating pipes, pre-swirls, and rim-seals, are generally articulated with characteristic curves that are extracted from high fidelity CFD modeling using commercial software such as Flowmaster or ANSYS-CFX. Having these curves, an algorithm is developed to calculate flow parameters at nodes with the aid of iterative methods. The procedure is based on three main innovative ideas. The first one is related to the network construction by defining a connectivity matrix which could be applied to any arbitrary network such as hydraulic or lubrication networks. In the second one, off-design SAS calculation will be proposed by introducing some SAS elements that their characteristic non-dimensional curves are influenced by their inlet total pressure. The last novelty is the integration of the blades coolant calculation process that incorporates external heat transfer calculation, structural conduction and coolant side modeling with SAS network simulation. Finally, SAS simulation of an industrial gas turbine is presented to illustrate capabilities of the presented tool in design point and off-design conditions