Abstract: In recent times, we noticed an interesting and important
role of non-coplanar degree-of-freedom (Φ = 00) in heavy ion
reactions. Using the dynamical cluster-decay model (DCM) with
Φ degree-of-freedom included, we have studied three compound
systems 246Bk∗, 164Yb∗ and 105Ag∗. Here, within the DCM with
pocket formula for nuclear proximity potential, we look for the
effects of including compact, non-coplanar configurations (Φc = 00)
on the non-compound nucleus (nCN) contribution in total fusion
cross section σfus. For 246Bk∗, formed in 11B+235U and 14N+232Th
reaction channels, the DCM with coplanar nuclei (Φc = 00) shows
an nCN contribution for 11B+235U channel, but none for 14N+232Th
channel, which on including Φ gives both reaction channels as
pure compound nucleus decays. In the case of 164Yb∗, formed in
64Ni+100Mo, the small nCN effects for Φ=00 are reduced to almost
zero for Φ = 00. Interestingly, however, 105Ag∗ for Φ = 00 shows a
small nCN contribution, which gets strongly enhanced for Φ = 00,
such that the characteristic property of PCN presents a change of
behaviour, like that of a strongly fissioning superheavy element to a
weakly fissioning nucleus; note that 105Ag∗ is a weakly fissioning
nucleus and Psurv behaves like one for a weakly fissioning nucleus
for both Φ = 00 and Φ = 00. Apparently, Φ is presenting itself like
a good degree-of-freedom in the DCM.
Abstract: In this paper, we first construct a new state and disturbance estimator using discrete-time proportional plus integral observer to estimate the system state and the unknown external disturbance for the discrete-time system with an input-to-output direct-feedthrough term. Then, the generalized optimal linear quadratic digital tracker design is applied to construct a proportional plus integral observer-based tracker for the system with an unknown external disturbance to have a desired tracking performance. Finally, a numerical simulation is given to demonstrate the effectiveness of the new application of our proposed approach.
Abstract: The objective of this theoretical study is to develop simple design formulas for the prediction of minimum film thickness and maximum mean film temperature rise in lightly loaded high-speed rolling/sliding lubricated elliptical contacts incorporating starvation effect. Herein, the reported numerical analysis focuses on thermoelastohydrodynamically lubricated rolling/sliding elliptical contacts, considering the Newtonian rheology of lubricant for wide range of operating parameters, namely load characterized by Hertzian pressure (PH = 0.01 GPa to 0.10 GPa), rolling speed (>10 m/s), slip parameter (S varies up to 1.0), and ellipticity ratio (k = 1 to 5). Starvation is simulated by systematically reducing the inlet supply. This analysis reveals that influences of load, rolling speed, and level of starvation are significant on the minimum film thickness. However, the maximum mean film temperature rise is strongly influenced by slip in addition to load, rolling speed, and level of starvation. In the presence of starvation, reduction in minimum film thickness and increase in maximum mean film temperature are observed. Based on the results of this study, empirical relations are developed for the prediction of dimensionless minimum film thickness and dimensionless maximum mean film temperature rise at the contacts in terms of various operating parameters.
Abstract: Sustainability is becoming a priority for developers and the use of environmentally friendly materials is increasing. Nowadays, the application of raw materials from renewable sources to building materials has gained a significant interest in this research area. Lignocellulosic aggregates and cellulosic fibers are coming from many different sources such as wood, plants and waste. They are promising alternative materials to replace synthetic, glass and asbestos fibers as reinforcement in inorganic matrix of composites. Natural fibers are renewable resources so their cost is relatively low in comparison to synthetic fibers. With the consideration of environmental consciousness, natural fibers are biodegradable so their using can reduce CO2 emissions in the building materials production. The use of cellulosic fibers in cementitious matrices have gained importance because they make the composites lighter at high fiber content, they have comparable cost - performance ratios to similar building materials and they could be processed from waste paper, thus expanding the opportunities for waste utilization in cementitious materials. The main objective of this work is to find out the possibility of using different wastes: hemp hurds as waste of hemp stem processing and recycled fibers obtained from waste paper for making cement composite products such as mortars based on cellulose fibers. This material was made of cement mortar containing organic filler based on hemp hurds and recycled waste paper. In addition, the effects of fibers and their contents on some selected physical and mechanical properties of the fiber-cement plaster composites have been investigated. In this research organic material have used to mortars as 2.0, 5.0 and 10.0 % replacement of cement weight. Reference sample is made for comparison of physical and mechanical properties of cement composites based on recycled cellulosic fibers and lignocellulosic aggregates. The prepared specimens were tested after 28 days of curing in order to investigate density, compressive strength and water absorbability. Scanning Electron Microscopy examination was also carried out.
Abstract: Connected vehicles are one of the promising technologies for future Intelligent Transportation Systems (ITS). A connected vehicle system is essentially a set of vehicles communicating through a network to exchange their information with each other and the infrastructure. Although this interconnection of the vehicles can be potentially beneficial in creating an efficient, sustainable, and green transportation system, a set of safety and reliability challenges come out with this technology. The first challenge arises from the information loss due to unreliable communication network which affects the control/management system of the individual vehicles and the overall system. Such scenario may lead to degraded or even unsafe operation which could be potentially catastrophic. Secondly, faulty sensors and actuators can affect the individual vehicle’s safe operation and in turn will create a potentially unsafe node in the vehicular network. Further, sending that faulty sensor information to other vehicles and failure in actuators may significantly affect the safe operation of the overall vehicular network. Therefore, it is of utmost importance to take these issues into consideration while designing the control/management algorithms of the individual vehicles as a part of connected vehicle system. In this paper, we consider a connected vehicle system under Co-operative Adaptive Cruise Control (CACC) and propose a fault diagnosis scheme that deals with these aforementioned challenges. Specifically, the conventional CACC algorithm is modified by adding a Kalman filter-based estimation algorithm to suppress the effect of lost information under unreliable network. Further, a sliding mode observer-based algorithm is used to improve the sensor reliability under faults. The effectiveness of the overall diagnostic scheme is verified via simulation studies.
Abstract: Due to the rapid growth in modern communication systems, fault tolerance and data security are two important issues in a secure transaction. During the transmission of data between the sender and receiver, errors may occur frequently. Therefore, the sender must re-transmit the data to the receiver in order to correct these errors, which makes the system very feeble. To improve the scalability of the scheme, we present a secure proxy signature scheme with fault tolerance over an efficient and secure authenticated key agreement protocol based on RSA system. Authenticated key agreement protocols have an important role in building a secure communications network between the two parties.
Abstract: Ubiquity of natural disasters during last few decades
have risen serious questions towards the prediction of such events
and human safety. Every disaster regardless its proportion has a
precursor which is manifested as a disruption of some environmental
parameter such as temperature, humidity, pressure, vibrations and
etc. In order to anticipate and monitor those changes, in this paper
we propose an overall system for disaster prediction and monitoring,
based on wireless sensor network (WSN). Furthermore, we introduce
a modified and simplified WSN routing protocol built on the top
of the trickle routing algorithm. Routing algorithm was deployed
using the bluetooth low energy protocol in order to achieve low
power consumption. Performance of the WSN network was analyzed
using a real life system implementation. Estimates of the WSN
parameters such as battery life time, network size and packet delay are
determined. Based on the performance of the WSN network, proposed
system can be utilized for disaster monitoring and prediction due to
its low power profile and mesh routing feature.
Abstract: This article is about first step of structural health monitoring by identifying structural system in the presence of unknown input. In the structural system identification, identification of structural parameters such as stiffness and damping are considered. In this study, the Kalman filter (KF) design for structural systems with unknown excitation is expressed. External excitations, such as earthquakes, wind or any other forces are not measured or not available. The purpose of this filter is its strengths to estimate the state variables of the system in the presence of unknown input. Also least squares estimation (LSE) method with unknown input is studied. Estimates of parameters have been adopted. Finally, using two examples advantages and drawbacks of both methods are studied.
Abstract: The present study investigated various forms of disciplinary procedures or punishment used by teachers in secondary schools in Calabar Municipality, Nigera. There are agitations amongst parents and educators on the use of corporal punishment as a disciplinary measure against children. Those against the use of corporal punishment argue that this form of punishment does not teach, it only terminates behaviour temporarily and inculcates violence. Those in support are of the view that corporal punishment serves as a deterrent to others. This study sought to find out the most common measure of discipline employed by teachers in private and public schools. The study had three objectives, three research questions and two hypotheses. The design of the present study was the ex-post facto descriptive survey, since variables under study were not manipulated by the researcher. Teachers in Calabar Municipal Secondary Schools formed the population. A sample of 160 teachers was used for the study. The data collection instrument was a facts finding questionnaire titled Disciplinary Procedures Inventory. Data collected were analyzed using simple percentages and chi-square. The major findings were that physical measures such as flogging, exercise/drills, and painful postures were commonly used by teachers in secondary schools. It was also found that these measures were more often used in public schools. It was recommended that teachers should rather employ non-violent techniques of discipline than physical punishment.
Abstract: Structures such as buildings, bridges, dams, wind turbines etc. need to be maintained against various factors such as deterioration, excessive loads, environment, temperature, etc. Choosing an appropriate monitoring system is important for determining any critical damage to a structure and address that to avoid any adverse consequence. Structural Health Monitoring (SHM) has emerged as an effective technique to monitor the health of the structures. SHM refers to an ongoing structural performance assessment using different kinds of sensors attached to or embedded in the structures to evaluate their integrity and safety to help engineers decide on rehabilitation measures. Ability of SHM in identifying the location and severity of structural damages by considering any changes in characteristics of the structures such as their frequency, stiffness and mode shapes helps engineers to monitor the structures and take the most effective corrective actions to maintain their safety and extend their service life. The main objective of this study is to review the overall SHM process specifically determining the natural frequency of an instrumented simply-supported concrete beam using modal testing and finite element model updating.
Abstract: In present paper, the performance of various alternative refrigerants is compared to find the substitute of R22, the widely used hydrochlorofluorocarbon refrigerant in developing countries. These include the environmentally friendly hydrofluorocarbon (HFC) refrigerants such as R134A, R410A, R407C and M20. In the present study, a steady state thermodynamic model (includes both first and second law analysis) which simulates the working of an actual vapor-compression system is developed. The model predicts the performance of system with alternative refrigerants. Considering the recent trends of replacement of ozone depleting refrigerants and improvement in system efficiency, R407C is found to be potential candidate to replace R22 refrigerant in the present study.
Abstract: In order to analyze the status of a diesel engine, as well as conduct fault prediction, a new prediction model based on a gray system is proposed in this paper, which takes advantage of the neural network and the genetic algorithm. The proposed GBPGA prediction model builds on the GM (1.5) model and uses a neural network, which is optimized by a genetic algorithm to construct the error compensator. We verify our proposed model on the diesel faulty simulation data and the experimental results show that GBPGA has the potential to employ fault prediction on diesel.
Abstract: Catalytic wet air oxidation (CWAO) is normally carried out at elevated temperature and pressure. This work investigates the potential of NiO-CeO2 nano-catalyst in CWAO of paper industry wastewater under milder operating conditions of 90 °C and 1 atm. The NiO-CeO2 nano-catalysts were synthesized by a simple co-precipitation method and characterized by X-ray diffraction (XRD), before and after use, in order to study any crystallographic change during experiment. The extent of metal-leaching from the catalyst was determined using the inductively coupled plasma optical emission spectrometry (ICP-OES). The catalytic activity of nano-catalysts was studied in terms of total organic carbon (TOC), adsorbable organic halides (AOX) and chlorophenolics (CHPs) removal. Interestingly, mixed oxide catalysts exhibited higher activity than the corresponding single-metal oxides. The maximum removal efficiency was achieved with Ce40Ni60 catalyst. The results indicate that the CWAO process is efficient in removing the priority organic pollutants from wastewater, as it exhibited up to 59% TOC, 55% AOX, and 54 % CHPs removal.
Abstract: Efficient utilization of spectrum resources is a
fundamental issue of wireless communications due to its scarcity.
To improve the efficiency of spectrum utilization, the spectrum
sharing for unlicensed bands is being regarded as one of key
technologies in the next generation wireless networks. A number
of schemes such as Listen-Before-Talk(LBT) and carrier sensor
adaptive transmission (CSAT) have been suggested from this aspect,
but more efficient sharing schemes are required for improving
spectrum utilization efficiency. This work considers an opportunistic
transmission approach and a dynamic Contention Window (CW)
adjustment scheme for LTE-U users sharing the unlicensed spectrum
with Wi-Fi, in order to enhance the overall system throughput. The
decision criteria for the dynamic adjustment of CW are based on
the collision evaluation, derived from the collision probability of the
system. The overall performance can be improved due to the adaptive
adjustment of the CW. Simulation results show that our proposed
scheme outperforms the Distributed Coordination Function (DCF)
mechanism of IEEE 802.11 MAC.
Abstract: Education systems are complex and involve interactions between humans (teachers and students); media based technologies, lectures, classrooms, etc. to provide educational services. The education system performance is characterized by how well students learn, which is measured using student grades on exams and quizzes, achievements on standardized tests, among others. Advances in portable communications technologies, such as mobile phones, tablets, and laptops, created a different type of classroom, where students seem to engage in more than just the intended learning activities. The performance of more than one task in parallel or in rapid transition is commonly known as multitasking. Several operations in educational systems are performed simultaneously, resulting in a multitasking education environment. This paper surveys existing research on multitasking in educational settings, summarizes literature findings, provides a synthesis of the impact of multitasking on performance, and identifies directions of future research.
Abstract: This paper deals with study about fractional
order impulsive Hamiltonian systems and fractional impulsive
Sturm-Liouville type problems derived from these systems. The
main purpose of this paper devotes to obtain so called Lyapunov
type inequalities for mentioned problems. Also, in view point on
applicability of obtained inequalities, some qualitative properties such
as stability, disconjugacy, nonexistence and oscillatory behaviour of
fractional Hamiltonian systems and fractional Sturm-Liouville type
problems under impulsive conditions will be derived. At the end,
we want to point out that for studying fractional order Hamiltonian
systems, we will apply recently introduced fractional Conformable
operators.
Abstract: This research paper shows matrix technology models and examples of information systems in education (in the Republic of Croatia and in the Germany) in support of business, education (when learning and teaching) and e-learning. Here we researched and described the aims and objectives of the main process in education and technology, with main matrix classes of data. In this paper, we have example of matrix technology with detailed description of processes related to specific data classes in the processes of education and an example module that is support for the process: ‘Filling in the directory and the diary of work’ and ‘evaluation’. Also, on the lower level of the processes, we researched and described all activities which take place within the lower process in education. We researched and described the characteristics and functioning of modules: ‘Fill the directory and the diary of work’ and ‘evaluation’. For the analysis of the affinity between the aforementioned processes and/or sub-process we used our application model created in Visual Basic, which was based on the algorithm for analyzing the affinity between the observed processes and/or sub-processes.
Abstract: Essential oils of Heracleum persicum (Apiaceae) have been widely used from many years ago, but the difference of its properties among different populations have not been identified up to now. Hydrodistilation Clevenger type was used to obtaining the fruit essential oils of four populations of H. persicum from different localities in Iran, then they were characterized by GC-FID and GC-MS analyses. Some ecological factors were also measured. The oils of four populations were compared to determine the similarities and differences and the relationships between these factors and ecological factors. Based on the result, 18-32 different components were identified in four populations, while the percentage of the main components was higher in population with lower number of components. According to the statistical analyses of chemical components and ecological factors, it can be concluded that some ecological factors such as altitude, less humidity, high difference between day and night temperature and salty soil would lead to lower number of components in essential oil, whereas they consist the higher percentage.
Abstract: This paper explores efficient ways to implement various
media-updating features like news aggregation, video conversion,
and bulk email handling. All of these jobs share the property
that they are periodic in nature, and they all benefit from being
handled in a distributed fashion. The data for these jobs also often
comes from a social or collaborative source. We isolate the class of
periodic, one round map reduce jobs as a useful setting to describe
and handle media updating tasks. As such tasks are simpler than
general map reduce jobs, programming them in a general map
reduce platform could easily become tedious. This paper presents
a MediaUpdater module of the Yioop Open Source Search Engine
Web Portal designed to handle such jobs via an extension of a
PHP class. We describe how to implement various media-updating
tasks in our system as well as experiments carried out using these
implementations on an Amazon Web Services cluster.
Abstract: The sintering step in powder metallurgy (P/M) processes is very sensitive as it determines to a large extent the properties of the final component produced. Spark plasma sintering over the past decade has been extensively used in consolidating a wide range of materials including metallic alloy powders. This novel, non-conventional sintering method has proven to be advantageous offering full densification of materials, high heating rates, low sintering temperatures, and short sintering cycles over conventional sintering methods. Ti6Al4V has been adjudged the most widely used α+β alloy due to its impressive mechanical performance in service environments, especially in the aerospace and automobile industries being a light metal alloy with the capacity for fuel efficiency needed in these industries. The P/M route has been a promising method for the fabrication of parts made from Ti6Al4V alloy due to its cost and material loss reductions and the ability to produce near net and intricate shapes. However, the use of this alloy has been largely limited owing to its relatively poor hardness and wear properties. The effect of sintering temperature on the densification, hardness, and wear behaviors of spark plasma sintered Ti6Al4V powders was investigated in this present study. Sintering of the alloy powders was performed in the 650–850°C temperature range at a constant heating rate, applied pressure and holding time of 100°C/min, 50 MPa and 5 min, respectively. Density measurements were carried out according to Archimedes’ principle and microhardness tests were performed on sectioned as-polished surfaces at a load of 100gf and dwell time of 15 s. Dry sliding wear tests were performed at varied sliding loads of 5, 15, 25 and 35 N using the ball-on-disc tribometer configuration with WC as the counterface material. Microstructural characterization of the sintered samples and wear tracks were carried out using SEM and EDX techniques. The density and hardness characteristics of sintered samples increased with increasing sintering temperature. Near full densification (99.6% of the theoretical density) and Vickers’ micro-indentation hardness of 360 HV were attained at 850°C. The coefficient of friction (COF) and wear depth improved significantly with increased sintering temperature under all the loading conditions examined, except at 25 N indicating better mechanical properties at high sintering temperatures. Worn surface analyses showed the wear mechanism was a synergy of adhesive and abrasive wears, although the former was prevalent.