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In the global effort to curb energy consumption and promote a sustainable lifestyle for our societies, we must strive to lower our energy needs in all aspects of our lives. One of the biggest contributors to our energy requirements are the buildings we spend most of our time inside. Buildings’ energy consumption can take many forms, such as, air conditioning, heating, ventilation, and lighting systems in order to create a comfortable environment for the users. One way of reducing buildings’ energy consumption is the use of renewable resource for energy. The main aim of this research is to measure and assess the public perceptions, knowledge and awareness of the concept of renewable energy, with specific regards to the use of solar photovoltaic cells, as well as investigate the desire to spend on the installation of renewable energy sources. Data was collected through a survey questionnaire applied in Irbid governorate in the north of Jordan. The statistical SPSS program was used to analyze closed-ended questionnaires and obtain numerical results based on arithmetical averages and percentages. The results show people are adequately aware of the benefits of renewable energy and most would like to have photovoltaic cells installed. However, 54.35% of the study sample live in apartments and do not have the space for the installation. 70.1% are open to the idea of sharing the solar energy system with their neighbors. 50% thought that the photovoltaic cells affected the aesthetics of the architecture style of the buildings especially the more traditional styles. It is concluded that the government needs to build a large-scale solar energy project to sustainably produce electricity instead of relying on individuals who generally lack the ability or the space for such systems, taking in note that the general public supports such concepts.

This paper studies imperfect underlay device-to-device (D2D) association in spectrum-shared cellular networks. It addresses important system and design interference constraints, processing load limitations and transmit power constraints at D2D terminals. The paper proposes decentralized schemes for D2D communication between D2D terminals when downlink channel resources can be reused in the D2D network. The D2D transmitters are characterized considering their processing load limitation and allocated transmit power constraints. Moreover, the downlink channels that can be reused in the D2D network are quantified while meeting interference constraints imposed by the primary cellular network. Two schemes to identify reusable channels, which vary in terms of their efficiency, communication overhead requirement and implementation complexity, are described. Moreover, two D2D association schemes, namely the simultaneous and sequential D2D associations, are proposed and both aim to concurrently maximize the desired link quality and minimize the effect of interference effect at D2D receivers. Generalized analytical results that are applicable for various imperfect association scenarios are presented. The findings are applicable for any D2D channel models and performance metrics. They provide insights into various imperfect underlay D2D association scenarios under the practical system and design constraints.

This study proposes adaptive downlink association schemes for controlled device-to-device (D2D) communication in cellular networks. The proposed schemes utilise active devices under specific conditions to improve the network performance. Specifically, active devices are classified into two disjoint groups according to their individual quality of service (QoS) requirements from their base station (BS). The BS adaptively allocates downlink physical channels to meet individual QoS of devices using a minimal number of these available channels. The unused channels at each served device (in the first class) can be then utilised by that device to serve other devices from the second class, which are not served by the BS, via controlled D2D associations. Herein, D2D pair discovery as well as the conditions for establishing successful D2D association between the classified devices are treated. Furthermore, two D2D association schemes that vary in terms of their performance and implementation complexity to meet certain objectives at the device of interest are presented. The developed analytical results address the scenarios of idealised perfect and practical imperfect D2D association. Numerical results are provided to further explain the performance variations between the proposed association schemes under perfect and imperfect operation scenarios.

"Background: High awareness of cervical cancer (CC) risk factors is important to decrease the morbidity and mortality associated with CC. This study aimed to assess the knowledge level of Palestinian women about CC risk factors and to determine the factors associated with good knowledge. Methods: This was a national cross-sectional study. Adult women from hospitals, primary healthcare centers, and public spaces of 11 governorates in Palestine were recruited using a stratified convenience sampling. A translated-into-Arabic version of the validated CC awareness measure (CeCAM) was used to assess the knowledge about the 11 CC risk factors. For each correctly identified risk factor, the participant was given one point. The total score was calculated and was categorized into three categories: poor knowledge (0–3), fair knowledge (4–7), and good knowledge (8–11). Results: A total of 7223 participants completed the Arabic CeCAM (response rate = 89.3%) and 7058 questionnaires were included in the final analysis: 2655 from the Gaza Strip and 4403 from the West Bank and Jerusalem. Participants recruited from the Gaza Strip were younger, getting lower monthly incomes, and with less chronic diseases than participants recruited from the West Bank and Jerusalem. The most frequently identified risk factor was ‘having a weakened immune system’ (n = 5458, 77.3%) followed by ‘infection with a sexually transmitted infection’ (n = 5388, 76.3%). The least identified risk factor was ‘having many children’ (n = 1597, 22.6%). Only 1670 women (23.7%) had good knowledge of CC risk factors. Women living in the Gaza Strip were more likely than women living in the West Bank and Jerusalem to have good knowledge (25.2% vs 22.7%). Completing a secondary or diploma degree, being employed, and having a monthly income of ≥ 1450 NIS (around $450) were all associated with lower likelihood of having good knowledge of CC risk factors. Conversely, knowing someone with cancer was associated with higher likelihood of having good knowledge. Conclusion: The overall awareness of CC risk factors was low. There is a substantial need to establish educational programs to promote Palestinian women’s awareness of CC." "خلفية البحث: الوعي العالي بعوامل الخطر لسرطان عنق الرحم مهم لتقليل نسبة المرض والوفيات المرتبطة بسرطان عنق الرحم. هدفت هذه الدراسة إلى تقييم مستوى معرفة النساء الفلسطينيات حول عوامل خطر الإصابة بسرطان عنق الرحم وتحديد العوامل المرتبطة بالمعرفة الجيدة. منهجية البحث: كانت هذه دراسة مقطعية وطنية. تم اختيار المشاركات في هذا البحث من النساء البالغات و تم جمع البيانات من النساء من المستشفيات ومراكز الرعاية الصحية الأولية والأماكن العامة في 11 محافظة في فلسطين باستخدام عينة ملائمة طبقية. تم استخدام نسخة مترجمة إلى العربية من مقياس الوعي لسرطان عنق الرحم (CeCAM) لتقييم المعرفة حول عوامل الخطر ذات العلاقة بسرطان عنق الرحم. لكل عامل خطر تم تحديده بشكل صحيح ، تم إعطاء المشارك نقطة واحدة. تم حساب النتيجة الإجمالية وتم تصنيفها إلى ثلاث فئات: ضعف المعرفة (0-3) ، ومتوسطة (4-7) ، والمعرفة الجيدة (8-11). النتائج: أكمل ما مجموعه 7223 مشاركًا اختبار CeCAM باللغة العربية (معدل الاستجابة = 89.3٪) وتم تضمين 7058 استبيانًا في التحليل النهائي: 2655 من قطاع غزة و 4403 من الضفة الغربية والقدس. كان المشاركون من قطاع غزة أصغر سناً, ويحصلون على دخل شهري أقل ، ولديهم أمراض مزمنة أقل من المشاركين من الضفة الغربية والقدس. كان عامل الخطر الأكثر تحديدًا هو ""ضعف الجهاز المناعي"" (العدد = 5458 ، 77.3٪) متبوعًا بـ ""الإصابة بعدوى تنتقل عن طريق الاتصال الجنسي"" (العدد = 5388 ، 76.3٪). كان عامل الخطر الأقل تحديدًا هو ""إنجاب العديد من الأطفال"" (العدد = 1597 ، 22.6٪). فقط 1670 امرأة (23.7٪) لديهن معرفة جيدة بعوامل خطر الإصابة بالسكري. كانت النساء اللواتي يعشن في قطاع غزة أكثر عرضة من النساء في الضفة الغربية والقدس للحصول على معرفة جيدة (25.2٪ مقابل 22.7٪). إن إكمال الشهادة الثانوية أو الدبلوم ، والتوظيف ، والحصول على دخل شهري قدره 1450 شيكل إسرائيلي جديد (حوالي 450 دولارًا) ، كلها مرتبطة بانخفاض احتمالية امتلاك معرفة جيدة بعوامل خطر الإصابة بسرطان عنق الرحم. على العكس من ذلك ، ارتبطت معرفة شخص مصاب بالسرطان بارتفاع احتمالية امتلاك معرفة جيدة. الخلاصة: كان الوعي العام لعوامل الخطر ذات العلاقة بسرطان عنق الرحم منخفض. هناك حاجة جوهرية لإنشاء برامج تثقيفية لتعزيز وعي النساء الفلسطينيات ببرنامج سرطان عنق الرحم."

This study aimed to test the effect of corporate social responsibility through activities towards society and environmental activities on financial leverage and corporate performance, the study population consists of all companies listed on the Amman Stock Exchange. The study sample reached 187 companies for the period 2014-2017, to achieve the goals of the study; regression analysis was used to find out the effect of social and environmental responsibility on leverage and performance, the study reached the results that the social responsibility towards the society affects the financial leverage of the company while the environmental activities did not affect the financial leverage, responsibility for social and environmental activities did not affect the performance of companies, and there was a positive correlation between social and environmental responsibility and financial leverage, and a negative link was found between financial leverage and performance.

Additional file 2.

In the present study, the concentrations of nine heavy metals (Fe, Zn, Mn, Cu, Mg, Cr, Ni, Cd, and Pb) in six different imported dried fruit samples of different brands (Mangoes, black raisins, figs, apricots, plums, and cranberries) were determined by Flame Atomic Absorption Spectroscopy (FAAS) after wet digestion. Samples were collected from different stores in Amman, Jordan. The average concentration of the selected metals in the analyzed samples were found to be in the range of 1.70-8.70 (Fe), 0.15-0.72 (Zn), 0.09-0.59 (Mn), 0.07-0.46 (Cu), 2.5-53.4 (Mg), 0.06-0.15 (Cr), 0.17-0.29 (Ni), 0.01-0.05 (Cd), and 0.11-0.57 (Pb) µg/g. The highest concentrations of Fe, Zn, Mn, Mg, and Ni were found in dried figs, highest concentrations of Cr, Cd, and Pb were found in dried apricots, and highest concentrations of Cu was found in dried black raisins. The results obtained in this study showed that Mg and Fe have the highest concentrations in all analyzed samples, whereas, the lowest concentrations obtained were for Cd and Cr. The concentrations of the highly toxic metals (Pb and Cd) in the all analyzed samples were found to be below or in good agreement with the permissible limits set by different health organizations. The figures of merit obtained for the FAAS calibration curves are brilliant with good linearity (r2 > 0.99). The FAAS method was validated by determining limit of detection (LOD), limit of quantitation (LOQ), and percent recovery (%R) for all investigated metals. The results obtained in this work were compared with the literature reported values.

We investigate the secrecy performance of a multiuser diversity scheme for an interference-limited wireless network with a base station (BS), $N$ legitimate users, and an eavesdropper in the presence of a single dominant interferer. Assuming interference dominates noise power at the eavesdropper and at each legitimate user's receiver, the BS transmits information to the legitimate user with the $k$ th best (highest) signal-to-interference ratio. We derive a closed-form expression for the secrecy outage probability for an arbitrary $N$ and an asymptotic expression for a fixed $k$ and large $N$ . Furthermore, we derive a closed form asymptotic expression for the ergodic secrecy capacity of the $k$ th best user and shows that it scales like $O\left(\log (N)\right)$ for a fixed $k$ and large $N$ .

In this paper, we study the outage performance of multiuser mixed underlay radio frequency (RF)/multidestinations free-space optical (FSO) links. For RF links, we consider a secondary network with multiple users that can communicate with multiple destinations through a relaying node. The relay is equipped with an antenna array at the RF side, and it uses the amplify-and-forward (AF) protocol. The primary users (PUs) are equipped with multiple antennas at transmit and receive nodes. The RF link is subjected to the aggregate PUs interference effect on the secondary network. To reduce the effect of PUs interference on secondary network at the relay node, two interference cancellation (IC) schemes are adopted, which vary in terms of complexity and achieved performance. On the other hand, the multidestination FSO links can be exploited to further enhance the quality of the second hop, and their associated channel models account for pointing errors, intensity modulation/direct detection, and heterodyne detection. For the aforementioned system model, we obtain exact and asymptotic closed-form expressions for the end-to-end outage probability. To further enhance system performance, optimal power allocation between the two hops is obtained based on the derived asymptotic outage probability expressions.

This paper investigates the impact of primary network interference on the performance of cognitive multihop secondary network under various multiple-input multiple-output MIMO approaches per hop. Specifically, the cognitive system involves a secondary network with MIMO relays that use the amplify-and-forward (AF) protocol, and each of which shares the same spectrum resources of multiple primary users (PUs) transmit and receive stations. Two different receive array conditions, and hence processing approaches, per hop in the secondary network are treated separately, which are maximal ratio combining (MRC) for sufficiently spaced receive antennas to provide receive diversity gain and interference cancellation (IC) for insufficiently spaced antennas to reduce the effect of PUs interference. The latter approach involves two different algorithms that vary in terms of complexity and achieved performance, which are dominant receive interference cancellation (DRIC) and adaptive receive interference cancellation (ARIC). Moreover, for both approaches, the transmit array gain is achieved per hop through the low-complexity transmit antenna selection (TAS). In doing so, new analytical results for multihop secondary network’s end-to-end outage probability are developed. Moreover, simple asymptotic results for this outage performance in high SNR regime are provided, from which the achieved diversity and coding gains and the diversity-multiplexing trade-off can be extracted. In addition, to further enhance the secondary network, optimal power allocation among hops is obtained based on the asymptotic outage performance under the constraints of transmit power of a secondary transmit station and interference limit on the primary network. The developed analytical results in this work are validated through numerical and simulation results.

Small-signal models are useful tools to preliminary understand the dynamics of interconnected systems like modular dc-dc converters which find a wide range of industrial applications. This work proposes a state-space-based averaged small-signal model in symbolic form for a peak current-mode controlled parallel-input/parallel-output buck converter operating in the continuous-conduction mode. In modeling the converter power-stage each module is independently represented. For modeling the current-mode control the state-space algebraic approach is used to incorporate the current-mode control-law into the power-stage equations. For each module two parasitic elements in addition to the current-loop sampling action are included in the derivation. Furthermore, the control-to-output voltage transfer functions are presented in symbolic form for two cases of interest: the first when the converter has two non-identical modules to study the effect of inductor mismatch, and the second when the converter is composed of n-connected identical modules to assess the effect of varying the number of modules. All responses from PSIM cycle-by-cycle simulations are in good agreement with the mathematical model predictions up to half the switching frequency.

In this paper, we propose a distributed cluster formation (CF) and resource allocation (RA) framework for non-ideal non-orthogonal multiple access (NOMA) schemes in heterogeneous networks. The imperfection of the underlying NOMA scheme is due to the receiver sensitivity and interference residue from non-ideal successive interference cancellation (SIC), which is generally characterized by a fractional error factor (FEF). Our analytical findings first show that several factors have a significant impact on the achievable NOMA gain. Then, we investigate fundamental limits on NOMA cluster size as a function of FEF levels, cluster bandwidth, and quality of service (QoS) demands of user equipments (UEs). Thereafter, a clustering algorithm is developed by taking feasible cluster size and channel gain disparity of UEs into account. Finally, we develop a distributed $\alpha $ -fair RA framework where $\alpha $ governs the tradeoff between maximum throughput and proportional fairness objectives. Based on the derived closed-form optimal power levels, the proposed distributed solution iteratively updates bandwidths, clusters, and UEs’ transmission powers. Numerical results demonstrate that proposed solutions deliver a higher spectral and energy efficiency than traditionally adopted basic NOMA cluster size of two. We also show that an imperfect NOMA cannot always provide better performance than orthogonal multiple access under certain conditions. Finally, our numerical investigations reveal that NOMA gain is maximized under downlink/uplink decoupled (DUDe) UE association.

In this paper, resource allocation and interference mitigation are investigated for heterogeneous networks where the lowest tier consists of device-to-device (D2D) cells. In order to alleviate dead-zone problem, we first consider downlink/uplink (DL/UL) decoupling user association and quantify its capability on interference management and network-wide D2D performance enhancement. Second, we propose an UL fractional frequency reuse scheme where subband (SB) bandwidths are adaptively determined based on: 1) user equipment (UE) density; 2) e-node-B (eNB) density; and 3) on/off switching frequency of small cells. Obtained results show that the adaptive method significantly reduces the number of outage users. Thereafter, a novel concatenated bi-partite matching (CBM) method is proposed for joint SB assignment (SA) and resource block allocation (RA) of cellular UEs. Numerical results show that the CBM provides a close performance to exhaustive solution with greatly reduced running time. The CBM is then extended to a centralized mode selection, SA, and RA for D2D cells. Alternatively, we develop offline and online semi-distributed approaches where a D2D-cell can reuse white-list RBs (WRBs), which are not occupied by the adjacent small cells. In the former, D2D-cell members are not aware of intra-cell and inter-cell interference and uniformly distribute their maximum permissible power to WRBs. In the latter, we put D2D sum rate maximization into a convex form by exploiting the proximity gain of D2D UEs. Online distributed solution is then developed by message passing of dual variables and consistency prices. Finally, virtues and drawbacks of the developed approaches are compared and explained.

This paper investigates the effect of various operation parameters on the downlink user performance in overlaid small-cell networks. The case study considers closed-access small cells (e.g., femtocells), wherein only active authorized user equipment (UE) can be served, each of which is allocated a single downlink channel at a time. On the other hand, the macrocell base station can unconditionally serve macrocell UEs that exist inside its coverage space. The available channels can be shared simultaneously in the macrocell network and the femtocell network. Moreover, a channel can be reused only at the macrocell base station. The analysis provides quantitative approaches to model UE identities, their likelihoods of being active, and their likelihoods of producing interference, considering UE classifications, locations, and access capabilities. Moreover, it develops models for various interference sources observed from effective interference femtocells, considering femtocells capacities and operation conditions. The associated formulations to describe a desired UE performance and the impact of the number of available channels and the adopted channel assignment approach are thoroughly investigated. The results are generally presented for any channel models of interference sources and the desired source of the served UE. Moreover, specific channel models are then adopted, for which generalized closed-form analytical results for the desired UE outage probability performance are obtained. Numerical and simulation results are presented to further clarify the main outcomes of the developed analysis.

This study aimed to test the effect of corporate social responsibility through activities towards society and environmental activities on financial leverage and corporate performance, the study population consists of all companies listed on the Amman Stock Exchange. The study sample reached 187 companies for the period 2014-2017, to achieve the goals of the study; regression analysis was used to find out the effect of social and environmental responsibility on leverage and performance, the study reached the results that the social responsibility towards the society affects the financial leverage of the company while the environmental activities did not affect the financial leverage, responsibility for social and environmental activities did not affect the performance of companies, and there was a positive correlation between social and environmental responsibility and financial leverage, and a negative link was found between financial leverage and performance.