ANALISIS KINERJA SPECTRUM SENSING BERBASIS EIGENVALUE DENGAN DOUBLE THRESHOLD PADA COGNITIVE RADIO

Cognitive radio adalah salah satu solusi baru untuk mengatasi masalah kurang dimanfaatkannya spektrum frekuensi. Pada jaringan cognitive radio, pengguna sekunder (SU) diperbolehkan mengakses frekuensi ketika frekuensi tersebut tidak digunakan oleh pengguna primer (PU). Untuk menghindari interferensi, pengguna sekunder perlu mengetahui bahwa frekuensi sedang digunakan atau tidak. Proses ini disebut spectrum sensing. Pada tugas akhir ini, dibandingkan dua metode sensing yang berbasis nilai eigen yaitu detektor dengan double threshold dan detektor single threshold. Metode ini berbasis nilai eigen dari matriks kovariansi sinyal diterima dan menggunakan rasio antara nilai maksimum dan minimum eigen sebagai test statistics. Parameter yang dianalisis yaitu probability of detection dan nilai throughput. Hasil pada simulasi menunjukkan bahwa detektor double threshold memiliki nilai probability of detection lebih tinggi dibandingkan detektor single threshold, pengujian ini dilakukan pada berbagai kondisi SNR dan jumlah sampel yang dgunakan. Selain itu, nilai throughput maksimal yang dicapai detektor double threshold lebih tinggi dibandingkan detektor single threshold and membutuhkan waktu sensing atau jumlah sampel yang lebih sedikit untuk mencapai throughput maksimum. Kata kunci : cognitive radio; spectrum sensing; eigenvalue; double threshold

An insight into internet sector in Iraq

The internet is considered to be the most advanced technology today and a gateway to modern communication and the sharing of information, products, services, and technology. Nowadays, users want to be able to access anywhere and anytime several services and applications, which is increasing data traffic and triggering a mobile data explosion. Iraq has major problems in increasing the growth and use of the internet and changing the standard method of communication. This is a big challenge, however, since there are several variables that characterize this phase of transformation. In this paper, the problems, vision, and solutions are presented in details. This study aims to clarify the factors of internet use in Iraq by the use of an acceptable approach and by suggesting new solutions for all the presented problems. This work also, clarify the expected traffic and the mechanism to transform the traffic between local ISP’s networks (AS) internet exchange points

Evaluating the Knowledge for Integrating RM and VM Using BIM in the Iraqi Construction Sector

The construction industry plays a crucial role in the countries' economy, especially in the developed country. This point encourages the concerned institution to use new techniques and integrate many techniques and methods to maximize the benefits. The main objective of this research is to evaluate the use of risk management, value management, and building information modeling in the Iraqi construction industry. The evaluation process aims at two objectives. The direct objective was to evaluate the knowledge in risk management (RM), value management (VM), and building information modeling (BIM). The indirect objective was to support the participants with information related to the main items mentioned. The questionnaire survey was used as a data collection method. The participants in the survey were engineers from the Iraqi construction sector. The sample size was 121 engineers from 34 institutions with multidisciplinary backgrounds. The results showed that the engineers need to develop the training system and merge many methods and techniques in their institution to maximize the benefits using an integration model capable of dealing with the variable environment in construction, especially in developing countries like Iraq

Using stochastic model for lower financial risk management in refinery operation planning

Most Refineries historically models are deterministic, that is, they use nominal parameter values without taking into consideration the uncertainty in process, demands, refinery parameters, etc. And as a consequence, they are unable to perform risk management. In this paper a variety of methodologies for financial risk management in engineering decision have been already developed. We follow the approach presented by Barbaro and Bagajewicz (2004), who used two-stage stochastic programming model and you, can find all other approaches analyzed and discussed. The problem addressed here is that of determining the crude oil to purchase and decide on the production level of different products given predicts of demands. The profit is maximized taking into account revenues, crude oil costs, inventory costs, and lost demand costs. The model was tested using data from the Refinery owned by the State Oil Marketing Organization (SOMO) Company, Iraq. The results show that the stochastic model can forecast higher expected profit and lower risk compared to the deterministic model

Hybrid Metaheuristic Technique Based Tabu Search and Simulated Annealing

This paper presents hybrid technique using two metahueristic methods; which are simulated annealing (SA) and tabu search (TS). The aim is to exhibit the facility of adaptive memory in tabu search method to resolve the long computation times of simulated annealing metaheuristic method. This can be done by keeping the best path which is found in each iteration. As a result, the proposed hybrid technique gives the optimum solution by finding the shortest path with minimum cost when applied on travelling salesman problem (TSP) since it reduces the time complexity by finding the optimum path with a few numbers of iterations when compared with SA and TS

Digital design of minimally invasive endodontic access cavity

New minimally invasive endodontic cavities have been described and proposed to preserve dentin (and enamel) through strategic access, including point endodontic access cavity (PEAC). There is no consensus to what extent PEAC contributes to tooth's resistance to fracture, because there is no agreement on how PEAC should be performed. The purpose of the present study is to describe and classify four different types of PEACs and to examine if a dynamic navigation system /DNS) could allow planning and precisely executing these cavities in vitro. Forty TrueTooth TM Replica # 3-001 models, were randomly divided into four identical groups of ten and scanned using a cone bean computed tomography (OP-Maxio 300, Instrumentarium-Kavo, Finland). Then, four different access cavities were planned and performed by using DNS (Navident dynamic navigation system, ClaroNav, Toronto, ON, Canada). For each tooth, a different PEAC was designed to obtain endodontic access to the main mesio-buccal canal (MB1), resulting in a different location of the entry point on the occlusal surface of the tooth. Precision was evaluated by comparing deviation in the inclinations between the planned and real cavity. Data were recorded and statistically analyzed. DNS allowed preparation of minimally invasive "straight line" cavities, with some differences in the accuracy

Hybrid power control and contention window adaptation for channel congestion problem in internet of vehicles network

Technology such as vehicular ad hoc networks can be used to enhance the convenience and safety of passenger and drivers. The vehicular ad hoc networks safety applications suffer from performance degradation due to channel congestion in high-density situations. In order to improve vehicular ad hoc networks reliability, performance, and safety, wireless channel congestion should be examined. Features of vehicular networks such as high transmission frequency, fast topology change, high mobility, high disconnection make the congestion control is a challenging task. In this paper, a new congestion control approach is proposed based on the concept of hybrid power control and contention window to ensure a reliable and safe communications architecture within the internet of vehicles network. The proposed approach performance is investigated using an urban scenario. Simulation results show that the network performance has been enhanced by using the hybrid developed strategy in terms of received messages, delay time, messages loss, data collision and congestion ratio

Room temperature thermally evaporated thin Au film on Si suitable for application of thiol self-assembled monolayers in MEMS/NEMS sensors

Gold is a standard surface for attachment of thiol-based self-assembled monolayers (SAMs). To achieve uniform defect free SAM coatings, which are essential for bio/chemical sensing applications, the gold surface must have low roughness, and be highly orientated. These requirements are normally achieved by either heating during Au deposition or post deposition Au surface annealing. This paper shows that room temperature deposited gold, can afford equivalent gold surfaces, if the gold deposition parameters are carefully controlled. This observation is an important result as heating (or annealing) of the deposited gold can have a detrimental effect on the mechanical properties of the silicon on which the gold is deposited used in microsensors. The paper presents the investigation of the morphology and crystalline structure of Au film prepared by thermal evaporation at room temperature on silicon. The effect of gold deposition rate is studied, and it is shown that by increasing the deposition rate from 0.02 nm s-1 to 0.14 nm s-1 the gold surface RMS roughness decreases, whereas the grain size of the deposited gold is seen to follow a step function decreasing suddenly between 0.06 and 0.10 nm s-1. The XRD intensity of the preferentially [111] orientated gold crystallites is also seen to increase as the deposition rate increases up to a deposition rate of 0.14 nm s-1. Formation and characterization of 1-dodecanethiol on these Au coated samples is also studied using contact angle. It is shown that by increasing the Au deposition rate the contact angle hysteresis (CAH) decreases until it plateaus, for a deposition rate greater than 0.14 nm s-1, where the CAH is smaller than 9 degrees which is an indication of homogeneous SAM formation, on a smooth surface

Investigation and Statistical Analysis for Optimizing Surface Roughness, Cutting Forces, Temperature, and Productivity in Turning Grey Cast Iron

This paper investigated the influence of cutting parameters, including feed rate, cutting speed, tool nose radius, and wet or dry cutting conditions, on the resultant force, cutting edge/workpiece temperature, and surface roughness when turning grey cast iron. Results showed that increasing the feed rate increased the resultant force, cutting temperature, and surface roughness. At the same time, increasing the cutting speed and nose radius increased the cutting temperature, which in turn reduced the resultant force. For practical applications, basic mathematical calculations based on the sole effect of each parameter on the output of the experiments were used to estimate the extent of percentage increase in cutting temperature due to increasing feed rate, cutting speed, and nose radius. Similarly, the same approach was used to estimate the effect of increasing feed rate, cutting speed, and nose radius on average surface roughness. Results showed that increasing the feed rate increases the cutting temperature by 5 to 11% depending on the nose radius and cutting speed. On the other hand, increasing the cutting speed was found to have limited effect on cutting temperature with small nose radius whereas this effect increases with increasing the nose radius reaching about 11%. Increasing the nose radius also increases the cutting temperature, depending mainly on cutting speed, reaching a maximum of 21% at higher cutting speeds. Results also showed that increasing the feed rate increased the average surface roughness considerably to about 120% at high cutting speeds and a large nose radius. On the other hand, increasing the cutting speed and nose radius reduced the surface roughness (i.e., improved surface quality) by a maximum of 29 and 23%, respectively. In order to study the combined effects of the cutting parameters on the three responses, namely, the resultant cutting force, cutting temperature, and surface roughness, full factorial design and ANOVA were used, where it was found to be in good agreement with mathematical calculations. Additionally, the desirability function optimization tool was used to minimize the measured responses whilst maximizing the material removal rate

Identifying Barriers to Umbilical Cord Blood Banking in Jordan: A Cross-Sectional Survey of Obstetricians

Background: The expansion of umbilical cord blood (UCB) banking necessitates a greater understanding among obstetricians in order to responsibly inform parents about UCB collection and storage. Gaps in knowledge can compromise public UCB banking efforts and result in missed opportunities and public misguidance about UCB banking. Materials and Methods: A cross-sectional survey was disseminated among obstetricians in Amman, Jordan. The questionnaire aimed to evaluate obstetricians’ knowledge of and attitude toward UCB storage and applications, as well as current practice patterns. Results: Ninety-six obstetricians responded (55% response rate), most of whom were Jordanian (71%), female (83%), resident physicians (59%), and working in either private (43%) or public (42%) hospitals, with an average of 6.5 years in practice. Only 26% had personal experience in UCB collection, and 20% had received education on UCB collection. Nearly 75% said their hospitals lacked standard operating procedures, guidelines, or infectious disease screening for UCB units. Overall knowledge about UCB was moderate, and the internet was the most common information source (54%). Overall attitudes were positive, especially in desire to expand personal knowledge about UCB, integrate information into medical residency curricula, and establish a public UCB bank in Jordan. However, many believed that ethical (61%) and religious (56%) controversies surround UCB donation. Conclusion: This study identifies deficiencies in quality control and experience in UCB collection in Jordan, as well as areas of inadequate knowledge and ethical controversies among obstetricians. These issues contribute to public misinformation and limit public UCB donation programs, and requires improved medical education on this topi