Noise-based Transmit Reference Modulation:A Feasibility Analysis

Wireless sensor networks (WSNs) receive huge research interest for a multitude of applications, ranging from remote monitoring applications, such as monitoring of potential forest fires, floods and air pollution, to domestic and industrial monitoring of temperature, humidity, vibration, stress, etc. In the former set of applications, a large number of nodes can be involved which are usually deployed in remote or inaccessible environments. Due to logistic and cost reasons, battery replacement is undesired. Energy-efficient radios are needed, with a power-demand so little that batteries can last the lifetime of the node or that the energy can be harvested from the environment. Coherent direct-sequence spread spectrum (DSSS) based radios are widely employed in monitoring applications, due to their overall resilience to channel impairments and robustness against interference. However, a DSSS rake receiver has stringent requirements on precise synchronization and accurate channel knowledge. To obviate the complexity of a coherent DSSS receiver, particularly for low data rate sensor networks, a DSSS scheme that has fast synchronization and possibly low power consumption, is much desired. In this regard, this thesis studies a noncoherent DSSS scheme called transmit reference (TR), which promises a simple receiver architecture and fast synchronization. In traditional TR, the modulated information signal is sent along an unmodulated reference signal, with a small time offset between them. In this thesis, we present and investigate a variant of TR, called noise-based frequency offset modulation (N-FOM), which uses pure noise as the spreading signal and a small frequency offset (instead of a time offset) to separate the information and reference signals. The detection is based on correlation of the received signal with a frequency-shifted version of itself, which collects the transmitted energy without compromising the receiver simplicity. Analytical expressions on performance metrics, supplemented by simulation results, improve understanding of the underlying mechanisms and provide insights into utility of N-FOM in low-power WSNs. In point-to-point line-of-sight (LOS) communication, it was observed that the communication scheme has a minimal utility. The energy-detector type of receiver mixes all in-band signals, which magnifies the overall noise. Particularly, the self-mixing of the transmitted signal also elevates the noise level, which increases with a further increase in the received signal energy. Therefore, for a fixed set of system parameters, the performance attains an asymptote with increasing transmission power. The phenomenon also establishes a non-monotonic relation between performance and the spreading factor. It was observed that a higher spreading factor in N-FOM is beneficial only in a high-SNR regime. After developing an understanding of the performance degrading mechanisms, few design considerations are listed. It is found that a suitable choice of the receiver front-end filter can maximize the SNR. However, the optimal filter depends on received signal and noise levels. A practically feasible – albeit suboptimal – filter is presented which gives close to the optimal performance. Next, timing synchronization is considered. The implications of synchronization errors are analyzed, and a synchronization strategy is devised. The proposed synchronization strategy has little overhead and can be easily implemented for symbol-level synchronization. The N-FOM LOS link model is extended to assess the performance degradation due to interference. Performance metrics are derived which quantify the effects of multiple-user interference, as well as that from external interferers, such as WiFi. Since the correlation operation mixes all in-band signals, the total interfering entities are quadratically increased. The research shows the vulnerability of N-FOM to interference, which makes it optimistic to operate in a crowded shared spectrum (such as the ISM 2.4\,GHz band). We also observe an upper limit on the number of mutually interfering links in a multiple access (MA) network, that can be established with an acceptable quality. The scheme is further investigated for its resilience against impairments introduced by a dense multipath environment. It is observed that despite the noise enhancement, the N-FOM system performs reasonably well in a non-line-of-sight (NLOS) communication. The detection mechanism exploits the multipath channel diversity and leads to an improved performance in a rich scattering environment. An analytical expression for outage probability is also derived. The results indicate that a healthy N-FOM link with very low outage probability can be established at a nominal value of the received bit SNR. It is also found that the choice of the frequency offset is central to the system design. Due to multiple practical implications associated with this parameter, the maximum data rate and the number of usable frequency offsets are limited, particularly in a MA NLOS communication scenario. The analysis evolves into a rule-of-thumb criterion for the data rate and the frequency offset. It is deduced that, due to its limited capability to coexist in a shared spectrum, N-FOM is not a replacement for coherent DSSS systems. The scheme is mainly suited to a low data rate network with low overall traffic, operating in an interference-free rich scattering environment. Such a niche of sensor applications could benefit from N-FOM where the design goal requires a simple detection mechanism and immunity to multipath fading

Molluscicidal Activity of Legumes, Yellow Flame (Peltophorum Pterocarpum) and Raintree (Samanea Saman) on Freshwater Snails; Indoplanorbis Exustus (Pulmonata: Planorbidae) and Radix Quadrasi (Pulmonata: Lymnaeidae)

Acute toxicity by static bioassay of ground dried leaves (medium age) of leguminoses, yellow flame (Peltophorum pterocarpum) and rain tree (Samanea saman), in the form of ground powder solution, crude water and methanol extract was determined against target freshwater snails, Indoplanorbis exustus (Planorbidae) and Radix quadrasi (Lymnaeidae), and also on non-target species, red tilapia, Oreochromis niloticus, and shrimp, Macrobrachium lanchesteri using static bioassay technique. The field-collected snails were examined for the infection of trematode larvae. 1. exustus was found to be the host to the two types of trematodes larvae (cercaria), namely furcocercous cercariae, bifurcated cercaria (schistosoma) and gymnocephalus cercariae, non-bifurcated tail cercaria (fasciola), whereas, R. quadrasi was found to be the host to the various types of gymnocephalus cercariae. The toxicity results indicated that molluscicidal and piscicidal activity is not limited to any particular plant species and that the dried ground leaves powder, crude water, and methanol extract; of P. plerocarpum and S. saman are toxic to the target and non-target species. However, toxicity of the crude methanol extracts of these plants exhibited the highest potency as compared to the crude water extract and dried ground leaves. The 24 h LC50 of crude water and methanol extract of P. pterocarpum against the target species was found to be within the standard range of World Health Organization (l00 mgtl) of being molluscicidally active. Based on the 24h LC50 values, the results indicated that the potency of P. pterocarpum treatments on the target snail species follow this trend; crude methanol extract (50.7- 55.6 mgtl) was the most potent, followed by crude water extract (64.9-72.7 mgtl) and the dried, ground powder (338.2-390.4 mgtl). Comparison test between 1. exustus and R. quadrasi showed that R. quadrasi was more sensitivity to crude methanol extract of P. pterocarpum than the S. saman, with 24h LCso value of 50.7 mg/l and 1 08 mgtl, respectively. Test carried out on the non-target species, shrimp, M lanchesteri was observed to be virtually absence of the toxic effect when exposed at the concentrations that kill 50% of the target snail species. But, red tilapia, 0. niloticus was more susceptible and LCso was obtained at the lower concentrations than the concentration that caused 50% mortality of the target snail species. The relationship of 24h LCso values to the different snail shell length of laboratory breed R. quadrasi and 1. exustus was also investigated using crude methanol extract of P. pterocarpum. Results indicated that the relationship between different shell length of R. quadrasi and 24h LCso was a positively correlated with r = 0.98, but the relationship was polynomial (quadratic) with the equation line of Y= 0.63 x2 -8.5x +42.7. In the case of 1. exuslus there was positive correlation between its sensitivity and its sizes, and relationship was linear with regression line of Y=2.77 x +8.3 and r of 0.96

EVALUATION OF IMPACT TO PISA SUCCESS OF SCHOOL-BASED MANAGEMENT POLICIES

In this study, countries with the highest levels of achievement according to math and science scores in the PISA exams and countries with the lowest levels of achievement were compared in terms of school-based management policy indicators in education. This research is a quantitative research method. The research is in statistical scanning model. Data are taken directly from EUROSTAT, OECD and PISA database. The educational systems of the countries with the highest scores in the PISA exams and the countries with the lowest scores were compared. It is seen that local governments have more funding for schools, schools have the authority to determine their own teachers, schools have the authority to determine the textbooks, students have the authority to evaluate student achievement and the school budget, and these rates are above the OECD average. In high score countries inter-school disadvantage was below the OECD average. In low score countries inter-school disadvantage was above the OECD average.   Article visualizations

Is the environmental Kuznets curve related to the fishing footprint? Evidence from China

This study tests the validity of the environmental Kuznets curve (EKC) hypothesis by using the fishing grounds footprint (FGF) as the environmental degradation indicator in China from 1961 to 2017. The study also uses China's total fisheries production as a control variable. Since the results of the analysis indicate a long-run relationship between the variables, we estimate the long- and short-run coefficients that present evidence for the validity of the EKC in the long-run. We find that total fisheries production has a detrimental effect on the environment. The findings of the study have important policy implications for decision-makers: Implementing a common fishing policy at the regional and global levels to stabilize the FGF and using new technologies that are harmless to the environment at every stage of fishery production processes may be beneficial for the environment. © 2022 Elsevier B.V

A Review of Cluster Head Selection Schemes in Wireless Sensor Network for Energy Efficient Routing Protocol

Energy management in Wireless Sensor Network (WSN) has attracted much concern due to the fact that the sensors are battery powered, and are usually deployed in hostile and inaccessible environments. With data transmission being the most energy consuming process in the network, several routing protocols based on clustering have been developed for energy efficient data transmission. The challenge of the clustering process in these protocols is the selection of Cluster Heads (CHs). This is due to the use of resource blind random generated number, high cost of network overhead, non-consideration of nodes’ residual energy, and/or location to ensure even distribution of CHs. This paper reviewed energy efficient cluster based routing protocols for WSN and proposed better approaches to mitigate these problems in order to improve network stability and lifetime

Assessment of teachers' perceptions of organizational citizenship behaviors and psychological empowerment: An empirical analysis in Turkey

Organizational citizenship behaviors (OCM) are discretionary individual behaviors that are not directly recognized by the reward system, but in the aggregate promote the overall effectiveness and functioning of the organization. Scholarly concern in OCB has increased dramatically over the past two decades. Nevertheless, there are significant research gaps and key issues yet to he addressed. Furthermore, employee empowerment can be conceptualized as the symbolic construction of the personal state of employees characterized by competence, or the skill and ability to perform effectively, and control, or the authority and autonomy to act. The main purpose of our study is to measure of organizational citizenship behaviors and psychological empowerment on teachers.This empiric research is planned to be realized by surveying method. Teachers in province Bursa have been reached and asked to participate in the study. We reached to 332 participants. The survey instrument included organizational citizenship behaviors, psychological empowerment and demographic questions about the participants. (C) 2013 The Authors. Published by Elsevier Ltd

Seawater salinity modelling based on electromagnetic wave characterization

Wireless communications have experienced tremendous growth, and improving their performance based on specific parameters requires an accurate model. Salt seawater, being an abundant resource, could play a crucial role in various applications such as enhancing electrical conductivity, monitoring security, improving battery power efficiency, and creating liquid antennas. Salinity is an essential factor to consider when developing these applications. This paper focused on investigating the electromagnetic properties of seawater salinity in the context of marine wireless communications. The results of the study showed that salinity has a significant impact on the Fresnel reflection coefficient in terms of magnitude, phase shift, and polarization, and can either constructively or destructively affect it. The new model paved the way for the development of an integrated salt seawater model that addressed the complex salinity issues involved in these applications

Performance of Some Forages Species (\u3cem\u3eFestuca arundinacea\u3c/em\u3e L., \u3cem\u3eChloris gayana\u3c/em\u3e var. Katambora, \u3cem\u3eLotus corniculatus\u3c/em\u3e L. and \u3cem\u3eMedicago sativa\u3c/em\u3e L.) in Saline Soil

Salinity is a soil degradation process which reduces plant diversity and agricultural productivity, decreases fertility and devalues the land in regions with arid and semi-arid climate. This process inhibits water and nutrient intake of plants from soil due to changeable nitrogen percentage and/or the intensity of soluble salt concentration. When the fact that agricultural lands are limited around the world and that the need for nutrition increases incrementally is taken into consideration, it is obvious that available lands should be used more effectively. Hence, it is quite crucial to reclaim saline soil and utilize it more economically (Woods 1996)