Performance evaluation of decode and forward cooperative diversity systems over nakagami-m fading channels with non-identical interferers

The deficiencies of regular cooperative relaying schemes were the main reason behind the development of Incremental Relaying (IR). Fixed relaying is one of the regular cooperative relaying schemes and it relies on using the relay node to help in transmitting the signal of the source towards the destination despite the channel’s condition. However, adaptive relaying methods allocate the channel resources efficiently; thus, such methods have drawn the attention of researchers in recent years. In this study, we analyze a two-hop Decode-and-Forward (DF) IR system’s performance via Nakagami-m fading channels with the existence of the several L distinguishable interferers placed close to the destination which diminishes the overall performance of the system due to the co-channel interference. Tight formulas for the Bit Error Rate (BER) and the Outage Probability (OP) are drawn. The assumptions are consolidated by numerical calculations

Dinamička distribucija sigurnosnih ključeva i koalicijski protokol IP adresa za mobilne ad hoc mreže

In mobile adhoc networks (MANETs) a tree-based dynamic address auto-configuration protocol (T-DAAP) is one of the best protocols designed for address assignment as far as the network throughput and packet delays are concerned. Moreover, MANET security is an important factor for many applications given that any node can listen to the channel and overhear the packets being transmitted. In this paper, we merge the address assignment with the security key delivery into one protocol, such that a node in the MANET is configured with IP address and security key simultaneously. To the best of our knowledge, no single protocol provides concurrent assignment of IP addresses and security keys for MANET nodes. The proposed method, which is based on T-DAAP, shows significant enhancements in the required control packets needed for assigning network nodes IP addresses and security keys, MAC layer packets, total end-to-end delay, and channel throughput over those obtained when using separate protocols. Additionally, it provides not only efficient security keys to the nodes from the first moment they join the network, but also secure delivery of the address and security key to all participating nodes. It is noteworthy to mention that providing a complete security model for MANET to detect and countermeasure network security threats and attacks is beyond the scope of our proposed protocol.Kod mobilnih ad hoc mreža (MANET) dinamički protokol za autokonfiguraciju adresa baziran na stablu (T-DAAP) je jedan od najboljih protokola dizajniranih za dodjelu adresa iz perspektive propusnosti mreže i i kašnjenja paketa. štoviše, sigurnost MANET-a je važan faktor za mnoge aplikacije s obzirom da bilo koji čvor može osluškivati kanal i slučajno čuti pakete koji se šalju. U ovom radu, dodjela adresa i dostava sigurnosnih ključeva spojeni su u jedan protokol tako da je čvor u MANET-u konfiguriran simultano s IP adresom i sigurnosnim ključem. Prema saznanjima autora, niti jedan postojeći protokol ne pruža istovremeno dodjeljivanje IP adrese i sigurnosnog ključa za MANET čvorove. Predložena metoda, koja se bazira na T-DAAP-u, pokazuje značajna poboljšanja u odnosu na metode koje koriste odvojene porotokole, kod traženih kontrolnih paketa koji su potrebni za dodjeljivanje IP adresa i sigurnosnih ključeva čvorovima mreže, MAC paketa, ukupnog end-to-end kašnjenja i propusnosti kanala. Dodatno pruža ne samo efikasne sigurnosne ključeve čvorovima od trenutka kad se priključe mreži, nego i sigurno dostavljanje adrese i sigurnosnog ključa svim čvorovima koji sudjeluju u mreži. Važno je spomenuti da je pružanje cjelokupnog sigurnosnog modela za MANET koji detektira dodatno i protumjere prijetnjama i napadima na sigurnost mreže izvan dosega predloženog protokola

The normal dimensions of the sella turcica in Jordanians: a study on lateral cephalograms

Background: The sella turcica is an important anatomic and radiologic entity. The dimensions of the sella turcica vary greatly in normal individuals and are influenced by genetic and local factors. The main objective of this study is to build up a normative database of the dimensions of the sella turcica in the Jordanian population. Materials and methods: For this purpose 509 computed cephalograms of 252 male and 257 female healthy Jordanians aged 10–40 years were collected and divided into two adolescent and adult age-groups for both genders. Viewbox 3 software was used to determine linear dimensions and area of the sella turcica. Results: Our results showed that the overall values for width, length, height, area, and aperture (interclinoid distance) were 8.72, 7.68, 6.25, 40.80, 3.92, and 8.67, 7.42, 6.38, 41.26, 3.68 mm (mm2) for males and females, respectively. Significant differences were found between adult male group on one hand and adolescent female group and adult female group on the other hand. Between age categories and within male and female groups, sella parameters were significantly different between adolescent and adult age-groups. Conclusions: Our data clearly confirm the classical notion of general trend of increase in parameters with age, irrespective of gender, with the area scoring the highest increase, and the height in females and length in males contributing most obviously to this trend. The aperture appears to decrease in females while it increases in males as adulthood is reached. This seems to reflect differential growth of the pituitary gland under neurohormonal effects

Scaling and optimisation of lateral super-junction multi-gate MOSFET for high drive current and low specific on-resistance in sub–50 V applications

The scaling of a non-planar super-junction (SJ) Si MOSFET based on SOI technology for low voltage rating applications (below 50 V) requires a subsequent optimisation of SJ unit. The scaling and the SJ optimisation are carried out with physically based commercial TCAD device simulations by Silvaco. The study is based on a meticulous calibration of drift-diffusion simulations against experimental characteristics of a 1 μm gate length SJ multi-gate MOSFET (SJ-MGFET) aiming at improving density, switching speed, drive current, breakdown voltage (BV), and specific on-resistance (Ron,sp). We investigate scaling of the device architecture to improve the device performance by optimising doping profile to achieve an avalanche-enabled device under a charge balanced condition. The optimised SJ-MGFETs scaled by a factor of 0.5 and 0.25, with a folded alternating U-shaped n/p-SJ drift region pillar of a width of 0.3 μm and a trench depth of 2.7 μm, achieve a low specific on-resistance (Ron,sp) of 7.68 mΩ⋅mm2 and 2.24 mΩ⋅mm2 (VGS = 10 V) and BV of 48 V and 26 V, respectively. The scaled 0.5 μm and 0.25 μm gate length SJ-MGFETs offer a transconductance (gm) of 20 mS/mm and 56 mS/mm at a drain voltage of 0.1 V, respectively, greatly improving the levels of integration in a CMOS architecture

Once the shovel hits the ground : Evaluating the management of complex implementation processes of public-private partnership infrastructure projects with qualitative comparative analysis

Much attention is being paid to the planning of public-private partnership (PPP) infrastructure projects. The subsequent implementation phase – when the contract has been signed and the project ‘starts rolling’ – has received less attention. However, sound agreements and good intentions in project planning can easily fail in project implementation. Implementing PPP infrastructure projects is complex, but what does this complexity entail? How are projects managed, and how do public and private partners cooperate in implementation? What are effective management strategies to achieve satisfactory outcomes? This is the fi rst set of questions addressed in this thesis. Importantly, the complexity of PPP infrastructure development imposes requirements on the evaluation methods that can be applied for studying these questions. Evaluation methods that ignore complexity do not create a realistic understanding of PPP implementation processes, with the consequence that evaluations tell us little about what works and what does not, in which contexts, and why. This hampers learning from evaluations. What are the requirements for a complexity-informed evaluation method? And how does qualitative comparative analysis (QCA) meet these requirements? This is the second set of questions addressed in this thesis

Fuzzy-FMEA Theory Approach for Prioritizing Supply Chain Nervousness Factors

Global supply chain shocks and interruptions underscore the importance of supply chain nervousness (SCN). A clear understanding of nervousness in the event of a crisis allows an organization to make a good plan to deal with interruptions and future shocks. This study aims to develop a model for assessing nervousness parameters in the supply chains (SCs) by incorporating the fuzzy-FMEA theory and gray correlation approach to rank the SCN factors. The integrated model used in this study can improve the accuracy of outcomes when uncertainty exists in the SCN data. The results show that the most important nervousness factors are SC planning, visibility, stability, decision support systems, and SC flexibility. The developed SCN approach allows understanding and prioritizing SCN factors with more realistic and effective assessment. Findings offer beneficial insights for SCN prevention, and suggestions are made to identify nervousness mitigations. The outcomes of this research can be used by researchers and SC specialists to develop decision support systems

Fabrication of ZrO2-based nanocomposites for transuranic element-burning inert matrix fuel

ZrO2-based composites reinforced with 6.5 vol.% of carbon foam, carbon fiber, and graphite were fabricated using spark plasma sintering, and characterized using scanning electron microscopy and X-ray diffractometry. Their thermal properties were also investigated. The microstructures of the reinforced composites showed that carbon fiber fully reacted with ZrO2, whereas carbon foam and graphite did not. The carbothermal reaction of carbon fiber had a negative effect on the thermal properties of the reinforced ZrO2 composites because of the formation of zirconium oxycarbide. Meanwhile, the addition of carbon foam had a positive effect, increasing the thermal conductivity from 2.86 to 3.38 W m−1 K−1 at 1,100°C. These findings suggest that the homogenous distribution and chemical stability of reinforcement material affect the thermal properties of ZrO2-based composites