Clinical manifestations of Giardiasis in Iran

Context: Giardiasis has multiple clinical manifestations and its prevalence is relatively high in the Hamadan province of Iran. Aims: This study was conducted to determine the most frequent clinical signs and symptoms of Giardiasis in the Hamadan province of Iran in 2006. Setting and Design: This was a descriptive cross sectional study. Methods and Material: Sixty four patients infected with Giardia were recruited. Antiglidin anti-body and TTG tests were done to rule out celiac disease. Statistical analysis used: The data was entered into a computer and chi-square test was used for statistical analysis. Results: Of a total of 64 cases, 26 were females. Giardiasis was most common in cases aged 16-20 years old (20.3%), in males (59.4%) and in patients with the educational status of primary school (31.25%). The most frequent symptom was abdominal pain (42.1%). Conclusion: We found that the clinical manifestations of Giardiasis are similar to that of other gastrointestinal diseases such as celiac. So Giardiasis should be considered as the most probable diagnosis in patients with gastrointestinal problems

Multi-service highly sensitive rectifier for enhanced RF energy scavenging

Due to the growing implications of energy costs and carbon footprints, the need to adopt inexpensive, green energy harvesting strategies are of paramount importance for the long-term conservation of the environment and the global economy. To address this, the feasibility of harvesting low power density ambient RF energy simultaneously from multiple sources is examined. A high efficiency multi-resonant rectifier is proposed, which operates at two frequency bands (478-496 and 852-869 MHz) and exhibits favorable impedance matching over a broad input power range (40 to 10 dBm). Simulation and experimental results of input reflection coefficient and rectified output power are in excellent agreement, demonstrating the usefulness of this innovative low-power rectification technique. Measurement results indicate an effective efficiency of 54.3%, and an output DC voltage of 772.8 mV is achieved for a multi-tone input power of '10 dBm. Furthermore, the measured output DC power from harvesting RF energy from multiple services concurrently exhibits a 3.14 and 7.24 fold increase over single frequency rectification at 490 and 860 MHz respectively. Therefore, the proposed multi-service highly sensitive rectifier is a promising technique for providing a sustainable energy source for low power applications in urban environments

Multitone excitation analysis in RF energy harvesters—Considerations and limitations

© 2018 IEEE. The effect of multitone excitation on the dc response of a voltage-doubler radio frequency energy harvester is analyzed. Theoretical analysis as well as frequency and time domain (TD) simulations were conducted to clarify the findings. Measurements were also carried out to validate the results. The measured, simulations and theoretical results are in good agreement. This paper focuses on evaluating the performance of a voltage doubler rectifier under multitone excitation (input power is the same in the single-tone and multitone case). Based on TD and harmonic balance simulations, theoretical and measurement analyses, it is evident that the application of multiple tones simultaneously within the matched frequency band and with the same average available power results in a lower average output dc power when compared with the single-tone case with the same input power. This trend is evident over a broad low input power range of −50 to −10 dBm (0.01–100 µW)

Power Flow Control in Multi-Terminal HVDC Grids Using a Serial-Parallel DC Power Flow Controller

© 2013 IEEE. Multi-terminal HVDC (MT-HVDC) grids have no capability of power flow control in a self-sufficient manner. To address this important issue, utilization of dc-dc high power and high-voltage converters is motivated. However, proposing suitable partial-rated dc-dc converters as well as their suitable modeling and control in both primary and secondary control layers as well as the stability analysis are the existing challenges that should be alleviated beforehand. This paper addresses the control of power flow problem through the application of a power converter with a different connection configuration, namely, serial parallel dc power flow controller (SPDC-PFC). The SPDC-PFC input is the transmission line voltage, and its output is transmission line current. Therefore, employing a full-power dc-dc converter is avoided as a merit. Additionally, in this paper, the common two-layer MT-HVDC grid control framework comprised of primary and secondary layers is efficiently modified in order to integrate the SPDC-PFC. A differential direct voltage versus active power droop control scheme is applied to the SPDC-PFC at the local control layer, guaranteeing dynamic stability, while an extended dc power-flow routine - integrating the SPDC-PFC - is developed at the secondary control layer to ensure the static stability of the entire MT-HVDC grid. The proposed control framework enables the SPDC-PFC to regulate the flow of current/power in the envisioned HVDC transmission line. From the static and dynamic simulation results conducted on the test CIGRE B4 MT-HVDC grid, successful operation of the proposed SPDC-PFC and control solutions are demonstrated by considering power flow control action. In more detail, the SPDC-PFC successfully regulates the compensated lines' power to the desired reference both in static and dynamic simulations by introducing suitable compensation voltages. In addition, good dynamic performance under both SPDC-PFC power reference and wind power-infeed change is observed

Determination of LC50 of copper in Litopenaeus vannamei

We determined the LC50 of copper (as CUSO_4) and it's Maximum Allowable Concentration (MAC) for Litopenaeus vannamei. The study was performed in 2003 for which bioassays were used for acute toxicity tests in a period of 96 hours during which water parameters such as water temperature, pH, dissolved oxygen, hardness, alkalinity were also measured. Ten treatments and three replicates for each treatment were used. A LC50 of 86.71, 27.28, 7.98 and 3.90mg/1 and also Maximum Allowable Concentration of 8.671, 2.728, 0.798 and 0.390mg/1 were determined at 24, 48, 72 and 96 hours post exposure. Results showed that L. vannamei is relatively resistant to copper. Hence, short period application of copper to white shrimp farms for controlling algal bloom is judged harmless to the fish

Soil moisture remote sensing using SIW cavity based metamaterial perfect absorber

Continuous and accurate sensing of water content in soil is an essential and useful measure in the agriculture industry. Traditional sensors developed to perform this task suffer from limited lifetime and also need to be calibrated regularly. Further, maintenance, support, and deployment of these sensors in remote environments provide additional challenges to the use of conventional soil moisture sensors. In this paper, a metamaterial perfect absorber (MPA) based soil moisture sensor is introduced. The ability of MPAs to absorb electromagnetic signals with near 100% efficiency facilitates the design of highly accurate and low-profile radio frequency passive sensors. MPA based sensor can be fabricated from highly durable materials and can therefore be made more resilient than traditional sensors. High resolution sensing is achieved through the creation of physical channels in the substrate integrated waveguide (SIW) cavity. The proposed sensor does not require connection for both electromagnetic signals or for adding a testing sample. Importantly, an external power supply is not needed, making the MPA based sensor the perfect solution for remote and passive sensing in modern agriculture. The proposed MPA based sensor has three absorption bands due to the various resonance modes of the SIW cavity. By changing the soil moisture level, the absorption peak shifts by 10 MHz, 23.3 MHz, and 60 MHz, which is correlated with the water content percentage at the first, second and third absorption bands, respectively. Finally, a 6×6 cell array with a total size of 312mm×312mm has been fabricated and tested. A strong correlation between measurement and simulation results validates the design procedure

Addressing coverage problem in wireless sensor networks based on evolutionary algorithms

© 2017 University of Western Australia. Wireless Sensor Networks (WSNs) are the key part of Internet of Things, as they provide the physical interface between on-field information and backbone analytic engines. An important role of WSNs-when collecting vital information-is to provide a consistent and reliable coverage. To Achieve this, WSNs must implement a highly reliable and efficient coverage recovery algorithm. In this paper, we take a fresh new approach to coverage recovery based on evolutionary algorithms. We propose EMACB-SA, which introduces a new evolutionary algorithm that selects coverage sets using a fitness function that balances energy efficiency and redundancy. The proposed algorithm improves network's coverage and lifetime in areas with heterogeneous event rate in comparison to previous works and hence, it is suitable for using in disaster management

High-Sensitivity and Compact Time Domain Soil Moisture Sensor Using Dispersive Phase Shifter for Complex Permittivity Measurement

This article presents a time domain transmissometry soil moisture sensor (TDT-SMS) using a dispersive phase shifter (DPS), consisting of an interdigital capacitor that is loaded with a stacked four-turn complementary spiral resonator (S4-CSR). Soil moisture measurement technique of the proposed sensor is based on the complex permittivity sensing property of a DPS in time domain. Soil relative permittivity which varies with its moisture content is measured by burying the DPS under a soil mass and changing its phase difference while excited with a 114-MHz sine wave (single tone). DPS output phase and magnitude are compared with the reference signal and measured with a phase/loss detector. The proposed sensor exhibits accuracy better than ±1.2% at the highest volumetric water content (VWC = 30%) for sandy-type soil. Precise design guide is developed and simulations are performed to achieve a highly sensitive sensor. The measurement results validate the accuracy of theoretical analysis and design procedure. Owning the advantages of low profile, low power consumption, and high sensitivity makes the proposed TDT-SMS a good candidate for precision farming and internet of things (IoT) systems

Sensitive ambient RF Energy harvesting

Rectification of microwave signals to generate DC (Direct Current) power has become the subject of research since the 1950’s. Radio Frequency (RF) energy harvesting has experienced a rapid development in recent years due to the increasing number of RF transmitter sources producing an abundant ambient microwave energy waste. Furthermore, the development of wireless power transmission (WPT) technologies has triggered impetus for RF energy harvesting. Hence, RF energy scavenging is a promising solution as it has the potential to provide a viable energy source to meet upcoming demands. Efficient ambient RF energy scavenging is a very challenging issue, as it deals with the low RF power levels available in the environment. The scavengeable power levels are generally unknown and can vary unpredictably; therefore sparking research interest to develop highly sensitive RF energy scavengers to capture ambient RF signals over a range of low input power levels. This research focuses on a real life RF energy scavenging approach to generate electrical power in urban environments. It aims to develop highly sensitive and efficient ambient RF energy scavenging system and method to harvest a broad range of very low level ambient RF power. The feasibility of RF energy harvesting through field measurements and maximum available power analysis in metropolitan areas of Melbourne, Australia is investigated. Scavengeable ambient frequency sources with their associated available RF power levels were identified. RF field investigations and analysis identified the scavengeable levels of ambient RF power are lower than previous published works. Available bands vary considerably from location to location which are highly incoherent and are effected by environmental/free-space conditions. Furthermore, it is demonstrated that commercial frequency bands such as FM (88-108 MHz) and TV (470-890 MHz) provide optimal sources for power scavenging due to their suitable level of the ambient power at a variety of locations. Furthermore, cellular and wireless communication systems (800-1000 MHz) are recommended as alternative power scavenging sources. In order to investigate the feasibility of harvesting ambient EM (electromagnetic) energy from multiple sources (broadcasting and cellular systems) simultaneously, a new highly sensitive multi-resonant rectifier is proposed operating over a broad input power range (−40 to −10 dBm). The measurement results demonstrate that a two tone input to the proposed dual-band RF energy harvesting system can generate 3.14 and 7.24 times more DC power than a single tone at 490 and 860 MHz respectively, resulting in a measured effective efficiency of 54.3% for a dual-tone input power of −10 dBm. Real environmental measurements indicate the rectifier generates 39.38 µW by harvesting RF energy from two bands simultaneously. In order to increase the sensitivity and hence the output DC power, harvesting energy over a wider frequency band is investigated. Therefore, the feasibility of harvesting ambient EM energy from FM broadcasting band is examined. A highly sensitive rectenna is proposed which exhibits favourable impedance matching at 89-11 MHz over a broad range of low input power 50 to 10 dBm (0.01 to 100 µW). The proposed FM rectenna with 22% fractional bandwidth delivers a measured power conversion efficiency of 41% with single tone of −10 dBm. An innovative idea that arose from these investigations was an evaluation of the performance of a rectenna system which was embedded into low profile building materials. This enables to harvest ambient RF energy in urban environments, providing a unique way of delivering power to many low energy home or office devices. Based on the real environmental measurements, the embedded rectenna in plaster generates 175 μW of DC power by harvesting EM energy over the FM frequency band. Finally, the effect of multi-tone excitation (with constant total input power) on output DC power of the rectifier is analysed to facilitate the comparison between single tone and multiple tones. Various factors such as; different frequency spacing, low input power levels and random phase (incoherency) arrangements were considered in frequency and time domain analysis and also in measurements. It is demonstrated that the application of multiple tones simultaneously within the matched frequency band and with constant total input power results in a lower total average output power when compared with single-tone case with the same input power