184 research outputs found
Energy-Efficient Spectrum Sensing for Cognitive Radio Networks
No full textDynamic spectrum access employing cognitive radios has been proposed, in order to opportunistically use underutilized spectrum portions of a heavily licensed electromagnetic spectrum. Cognitive radios opportunistically share the spectrum, while avoiding any harmful interference to the primary licensed users. One major category of cognitive radios consists of is interweave cognitive radios. In this category, cognitive radios employ spectrum sensing to detect the empty bands of the radio spectrum, also known as spectrum holes. Upon detection of such a spectrum hole, cognitive radios dynamically share this empty band. However, as soon as the primary user appears in the corresponding band, cognitive radios have to vacate the band and look for a new spectrum hole. This way, reliable spectrum sensing becomes a key functionality of a cognitive radio network. The hidden terminal problem and fading effects have been shown to limit the reliability of spectrum sensing. Distributed cooperative detection has therefore been proposed to improve the detection performance of a cognitive radio network. In this thesis, a distributed detection scheme based on hard fusion of local results is considered. Each cognitive radio senses the spectrum and sends the result to the fusion center, and there the final decision is made about the presence or absence of the primary user. Note that, in general, cognitive radios are low-power sensors and thus energy consumption becomes a critical issue. In this thesis, several energy-efficient approaches are proposed, in order to minimize the maximum average energy consumption per sensor, while satisfying the sensing reliability of the cognitive radio network. The sensing reliability is defined by a lower bound on the probability of detection and an upper bound on the probability of false alarm. This way, the primary user is protected from the cognitive radio transmitter’s interference and also the chance of losing spectrum access through erroneous detection of the primary user in an empty band is constrained. First, a censoring scheme is considered where cognitive radios send their results to the fusion center only if they are deemed to be informative. Second, a combined censoring and truncated sequential sensing scheme is depicted which is shown to be more energy-efficient than the former case due to the sensing energy reduction. And third, a combined censoring and sleeping scheme is discussed where on top of censoring, each cognitive radio switches off its sensing module with a specific sleeping rate, in order to save energy both on transmission and sensing. It is shown that all the proposed schemes, particularly combined censoring and sleeping as well as censored truncated sequential sensing delivers significant energy savings. Further, we conclude that when a cognitive radio system is appropriately well-designed in terms of energy efficiency, increasing the number of cooperative cognitive sensors, not only improves the detection performance, but also reduces the average energy consumption of individual cognitive radios. Finally, an optimal fusion strategy for energy-constrained hard-fusion based cognitive radio networks is presented, which optimizes the network throughput subject to a constraint on the average energy consumption of individual radios and a constraint on the amount of interference to the primary user. It is shown that the majority rule is either optimal or close to optimal in terms of the network throughput.MicroelectronicsElectrical Engineering, Mathematics and Computer Scienc
The Effectiveness of Aloe Vera on Relief of Irritation and Nipple Pain in Lactating Women: Systematic Review and Meta-Analysis
No full textBackground. Aloe vera is one of the herbal products with anti-inflammatory, antioxidant, moisturizing, bactericidal, anti-viral, and anti-fungal effects that were used to relieve pain and irritation. The aim of the current systematic review and meta-analysis is to determine the effect of Aloe vera on the relief of irritation and nipple pain in lactating women. Methods. A search was carried out in four English electronic databases including Scopus, Embase, PubMed, and Web of Science until November 2021. All clinical trials that assessed the effect of Aloe vera on the relief of irritation and nipple pain in lactating women were included. The study’s risk of bias was assessed using the Cochrane risk of bias checklist. Study heterogeneity was determined using the I2 statistic and publication bias using Begg’s and Egger’s tests. Results of the random-effects meta-analysis were presented using standard mean difference (SMD) with 95% confidence intervals (CIs). Data were analyzed using STATA software version 16 MP. Results. In total, 7 articles with 1670 subjects were included in the meta-analysis. Overall, we found a positive impact of Aloe vera on reducing breast pain (pooled SMD= −0.45; CI= −0.83, −0.07, P value <0.02) and irritation (pooled SMD= −0.48; CI= −0.64, −0.32, P value<0.001) in lactating women. There is a high heterogeneity among pain studies (I2= 86%) but was low within irritation studies (I2= 26%). Conclusion. Our result showed that Aloe vera can be considered a choice for relieving breast pain or irritation in lactating women compared with routine care or another treatment. Considering the limited number of studies conducted on this topic and the low sample size, future studies with a larger sample will be required to draw better conclusions
Offline Power Allocation and Spectrum Sensing Strategy in Energy-Harvesting Cognitive Radio Networks
No full textEnergy-harvesting cognitive radio network has emerged as a solution to increase energy and spectrum efficiency. In this thesis, we propose short-term offline optimal power allocation algorithms for multi-user energy-harvesting cognitive radio networks considering interference between secondary users. Assuming finite and rechargeable batteries for secondary users and a time-slotted operation model, an off-line optimization problem is formulated so as to maximize the network throughput during finite time-period. To that aim, the design of a power allocation and the spectrum sensing strategy is required. Together with the inherent constraints imposed by the use of energy-harvesting devices, a collision constraint is also required to limit the probability of interference with the primary user and to guarantee the quality of service. Because of the intractability of the power allocation problem in the interference channel, we spilt the optimization task for two different size cognitive radio networks: a) 2-user network, and b) multi-user network (i.e. more than 2 users). The optimal algorithms are developed for a sharing single-frequency band, and a multi-band scenario for the two-user network. We derive the optimal solution following a two-step strategy in case of a 2-user energy-harvesting CR network. A suboptimal algorithm that entails reduced computational cost and performs very close to the optimal one is also proposed for the single-band sharing scenario. In case of multi-user energy-harvesting cognitive radio networks, a SQP-based sub-optimal algorithm is derived for single-band sharing scenario. Besides, a optimal solution is proposed for a CR network applying interference cancelation techniques sharing the single band. At last, we derive the optimal power allocation strategies for the multi-user multi-band sharing scenario. Simulation results of the optimal (and suboptimal) solutions outperform those achieved by a random or priority best-user power allocation algorithms for the AND and OR fusion rules.Electrical EngineeringTelecommunicationsElectrical Engineering, Mathematics and Computer Scienc
Enhancing Multivariate Geostatistical Simulation in Mine Tailings Using the Projection Pursuit Multivariate Transform and Coregionalization Analysis
No full textUnderstanding the spatial distribution of elements in mine tailing deposits is fundamental for resource reprocessing, economic feasibility studies, and environmental sustainability. Multivariate geostatistical simulation, commonly known as cosimulation or joint simulation, is a powerful method for capturing spatial variability and cross-correlation in these deposits. The accuracy of the modeling is strongly influenced by the inferred spatial cross-correlation structure, which reflects the complexity of tailings formed through variations in deposition processes, particle settling, and postdepositional modifications. Properly accounting for these nested structures ensures a more accurate representation of spatial dependence and multivariate relationships. Among the available techniques, sequential Gaussian cosimulation (SGCS) remains widely used, largely because of its integration into commercial software packages. However, its computational performance becomes a limitation when it is applied to large datasets involving multiple variables, as a full cokriging system must be solved for each variable at every simulation location. To address these challenges, decorrelation techniques have been introduced to streamline cosimulation workflows. Principal component analysis (PCA) and minimum/maximum autocorrelation factors (MAF) are commonly applied, but their effectiveness is constrained by structural limitations in the linear model of coregionalization (LMC). PCA guarantees decorrelation only for single-structure LMCs, whereas MAF is limited to at most two structures. Thus, both methods are inadequate for datasets with the nested spatial continuity characteristic of mine tailing deposits. The projection pursuit multivariate transform (PPMT) provides a more flexible alternative, effectively removing cross-correlations at a lag distance of zero. However, residual correlations may persist at larger lag distances, requiring additional transformations such as MAF, which remains limited by the number of structures in the LMC. This study develops a joint simulation algorithm that integrates the PPMT with cosimulation via coregionalization analysis to develop a factorization-based decorrelation technique across all nested LMC structures. Unlike traditional PCA, MAF, and PPMT-MAF, this approach is not restricted by the number of nested structures, making it a more adaptable solution for complex multivariate datasets. The proposed approach is tested on the Haveri mine tailing deposit, where Cu, Au, Fe, and S are jointly simulated to evaluate its effectiveness in handling decorrelation challenges in multivariate geostatistical simulations. The results confirm that this method provides a computationally efficient and flexible alternative to traditional cosimulation techniques, ensuring better preservation of global statistics and spatial continuity while maintaining the multivariate relationships essential for resource assessment.The first author (N. Madani) is grateful to Nazarbayev University for funding this work via the Collaborative Research Program 2023-2025 under contract No. 20122022CRP1614. The second author (M. Maleki) acknowledges funding from the National Agency for Research and Development of Chile through grant ANID Fondecyt 11220464.Peer reviewe
Penyelesaian pemrograman linier fuzzy trapesium dengan Mmenggunakan metode ranking function
No full textINDONESIA
Permasalahan pemrograman linier memiliki parameter antara lain jumlah produk yang harus diproduksi, jumlah bahan mentah yang tersedia terbatas atau jumlah tenaga kerja yang terampil terbatas. Parameter-parameter tersebut seringkali tidak dapat diprediksi secara pasti atau kabur (fuzzy). Oleh karena itu dalam tugas akhir ini penyelesaian masalah ketidakpastian tersebut menggunakan pemrograman linier fuzzy. Penyelesaian pemrograman linier fuzzy ini menggunakan metode ranking function. Metode ranking function merupakan metode untuk mengurutkan bilangan fuzzy yang didasarkan pada konsep perbandingan bilangan fuzzy. Perbandingan bilangan fuzzy merupakan cara yang paling efektif untuk menyusun bilangan-bilangan fuzzy. Setelah parameter fuzzy diselesaikan dengan metode ranking function, selanjutnya tinggal dioptimalkan dengan menggunakan metode algortima titik interior. Adapun studi kasus dalam tugas akhir ini permasalahan terdiri dari maksimasi dan minimasi. Untuk permasalahan maksimasi maupun minimasi diselesaiakan dengan menggunakan Maleki ranking function dan Yager ranking function. Dalam tugas akhir ini penulis mendapatkan nilai optimal PT Dakota Furniture untuk permasalahan maksimasi dengan Maleki ranking function yaitu , dan Yager ranking function 480 and Yager ranking function is $ 218. For the problem of minimizing the optimal value for factory problem with Maleki ranking function that is Rp 3.412.500 and Yager ranking function Rp 1.865.49
The Effect of Culture and Political Structure on Participatory Policy Analysis
No full textIn this research, the central objective was to explore how cultural and political factors might affect participatory practices of policy analysis. For this purpose, initially the concept of policy analysis and its evolutionary process from traditional and expert-based approach to participatory style, and role of context in policy analysis in general and participatory policy analysis in particular are studied. Next, the concept of public participation is elaborated through studying the levels and purposes of participation, type of participants, and the methods or techniques of public participation. Afterwards, risk and challenges of participation are enumerated, and a number of "factors of participation (FP)" which are sensitive to politico-cultural context are identified. Thirteen FPs are introduced and classified into four main categories of factors. Next, the cultural and political indicators which steers these FPs are explored. Hofstede's Theory, World Value Survey (WVS) by Inglehart, Schwartz cultural values orientations, cultural study of GLOBE project and Minkov cultural study, are the cross-cultural theories examined in order to extract measurable cultural indicators to explore the identified FPs. Subsequent to the recognition of cultural indicators three globally reputable research projects, namely Freedom in the World Survey, The Economist Intelligence Unit’s Index of Democracy and Worldwide Governance Indicators (WGI), in which governance indexes and democracy indicators are periodically calculated in the national level, are scrutinized in order to identify the most relevant political indicators to this thesis. Exploiting the relation between cultural and political indicators and factors of participation (FP), a framework is developed for each category of FPs. In this framework, each FP is evaluated by national scores of some cultural and/or political indicators, every FP has two poles which are assigned to extreme scores of relevant indicators and are distinguishable by specific attributes. In order to test the applicability of the developed framework, several national cases have been studied utilizing the framework. A comparative case study for a specific participatory method - consensus conference – would be done for some other countries. The case studies show that the framework can effectively explain the influence of contextual factors. Furthermore, the case studies are also helped to revise and improve the framework in a reciprocal process. It is revealed that the framework can provide awareness for policy analysts who want to employ participatory approach. This is in fact the descriptive application of the framework. Moreover, the framework can have the prescriptive application. Although this application should be elaborated in a separate research, the practical application of the framework initiates at the end of thesis. The implication of each FP's attributes is indicated and accordingly can guide the analysts to select and adapt the purpose and method of participation. Some relevant features of known public participation methods are introduced and a tentative example of practical considerations is demonstrated. The research concludes with an indication of the considerations about the research/framework and gives some suggestions for future research.Engineering and Policy AnalysisPolicy Analysis and ManagementTechnology, Policy and Managemen
Spectrum Sensing Issues for Cognitive Radio
No full textTelecommunicationElectrical Engineering, Mathematics and Computer Scienc
The effect of music-based interventions on short-term postpartum episiotomy pain: A systematic review and meta-analysis
No full textBackground: Episiotomy took over as the most common surgery in the field of midwifery that was performed in the second stage of labor to facilitate delivery, and reduce perineal damage. Music is one of the methods used to combat pain. We applied a meta-analysis to investigate whether music-based interventions can reduce short-term postpartum episiotomy pain. Four main English databases including Embase, PubMed, Web of Science, and Scopus were searched until July 2022. All randomized controlled trials (RCTs) with at least two groups (control and intervention) that aimed to measure the effect of music therapy on episiotomy pain were included in the present review. The Cochrane risk of bias checklist was used to assess study quality. Study heterogeneity was determined using the I2 statistic and publication bias using Begg’s and Egger’s tests. Results of random effect analysis are presented as Standard Mean Difference (SMD) with 95% confidence intervals (CI). Data were analyzed using the STATA software version 16. In total, seven articles with 677 subjects were included in the meta-analysis. Overall, the pool estimates of the meta-analysis demonstrated that music therapy has a positive impact on reducing short-term pain derived from episiotomy in both primiparous and multiparous compared to the control group (pooled SMD = −1.60; CI = −2.18, −1.02, p-value<0.001). The heterogeneity was high among including studies (I2 = 95.7%, p < 0.001). Our result showed that music-based interventions can be considered a choice for the management of short-term postpartum episiotomy pain among both primiparous and multiparous women. Future studies with large sample sizes and longer follow-up periods will be required to draw better conclusions about the long-term effects on postpartum pain
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