Architecture of an efficient dual band 1.8/2.5 GHz rectenna for RF energy harvesting

This paper presents a highly efficient rectenna of RF energy harvesting systems operating at 1.8 GHz and 2.5 GHz bands for battery-less sensor application. The antenna is designed by CST-MWS. The Schottky diode used for rectifying circuit is HSMS 286B in which designed by Agilent ADS. The key finding of the paper is that the simulated DC output voltage of the rectenna is 1.35 V for low input power of -25 dBm at a high resistance load of 1M Ω. Correspondingly, the RF-DC conversion efficiency of the rectification process is 59.51% and 45.75% at 1.8 GHz and 2.5 GHz, which are high efficiency and much better compared to literature respectively. The rectenna is capable to produce 1.8 V from an input power of -20 dBm. Thus, the proposed RF energy harvesting system offers a promising solution designed for efficient functionality at a low power level of RF energy in the dual band

Analisis prestasi penuai tenaga mikro frekuensi radio berkuasa rendah menggunakan antena MEMS bagi rangkaian sensor tanpa wayar

Kebelakangan ini, terdapat kecenderungan minat yang semakin meningkat dari para penyelidik menggunakan tenaga ambien bagi menghidupkan peralatan elektronik menggunakan pelbagai teknik penuaian tenaga. Penuaian tenaga mikro adalah teknik yang berpotensi untuk menukar tenaga ambien dari persekitaran kepada tenaga elektrik. Rangkaian sensor tanpa wayar memerlukan sumber tenaga elektrik yang berterusan untuk mengaktifkannya dan sumber tenaga ambien frekuensi radio (RF) yang sentiasa wujud dipersekitaran sangat sesuai digunakan. Oleh itu, penuai tenaga mikro RF yang direkacipta dan dibangunkan terdiri dari litar padanan galangan, pendarab voltan dan litar pengatur tidak memerlukan sumber tenaga luar untuk mengaktifkannya. Litar penuai tenaga mikro RF ini dibina dan disimulasi menggunakan perisian PSPICE dengan menyambungkan perintang beban 1 MΩ. Pada kuasa masukan -20 dBm atau 10 μW yang ditangkap oleh antena MEMS, nilai voltan dan arus keluaran yang dihasilkan dalam litar penuai tenaga ini masing-masing adalah 2.36 V dan 1.7 mA. Manakala, peratusan kecekapan maksimum bagi keseluruhan litar penuai tenaga mikro RF ini adalah 55.7%. Nilai kuasa keluaran yang dihasilkan iaitu 40.12 mW adalah lebih tinggi berbanding nilai kuasa masukan iaitu 10 μW. Penuai tenaga mikro RF ini mampu untuk mengaktifkan rangkaian sensor tanpa wayar dengan keperluan arus masukan minimum 1 mA. Susunatur litar bersepadu menggunakan teknologi CMOS 180 nm bagi litar pendarab telah berjaya dibangunkan dengan saiz yang sangat kecil iaitu 22.48 x 56.96 μm2 sebagai pembuktian litar boleh difabrikasi sebagai cip litar bersepadu

Development of a Hybrid Solar and Waste Heat Thermal Energy Harvesting System

This research aims to develop a Hybrid Solar and Waste Heat Thermal Energy Harvesting System that integrates Thermoelectric Generator (TEG) with a solar PV system. The main focus is given to the development of the hybrid solar and waste heat released from the solar panel by using the TEG system. This hybrid system consists of photovoltaic (PV) cells to absorb the solar energy and the TEG attached to the back of the panel to absorb heat waste and convert it into usable electricity. The PV cell and the TEG are integrated with each other in order to obtain maximum energy and increased system efficiency. The experimental results show that the maximum output voltage produced from the solar PV is 20.37V and the maximum output current generated is 203.72mA. The maximum output voltage obtained from the TEG is 18.92V and the maximum current produced is 189.265mA. This experimental result shows that the maximum voltage and current produced from solar and waste thermal heat from PV panels can be used to charge and to power up portable electronic devices. More efficiency is accomplished by combining the TEG to absorb waste heat loss from the PV cell, thus improving the performance of the PV panel system

Physical and Chemical Properties of Nano Zinc Oxide Modified Asphalt Binder

Recently, nanotechnology has been used in all fields of science, including pavement engineering due to promising and improvement of materials offered. The modification of asphalt binder has evolved gradually, with several types of nanomaterials being employed to modify the asphalt binder. In this study, nano zinc oxide with flake structure was used as a modifier in asphalt binder. The nano modifiers were blended with penetration grade 60/70 asphalt binder at 3%, 5%, and 7%, respectively. Physical properties of the modified asphalt binders were then examined, including storage stability, penetration, softening point, and viscosity. Meanwhile, the chemical property was determined using Fourier-Transform Infrared Spectroscopy. It was discovered that 3% nano zinc oxide produced the best results. Nano zinc oxide was found not to show separation at high temperatures in a storage stability test. The addition of nano zinc oxide to the asphalt binder also reduced the penetration, increased the softening point, and reduced the viscosity. The high penetration index value also indicates that the asphalt binder treated with nano zinc oxide is thermally resistant.   Keywords: Nanotechnology, asphalt binder, nano zinc oxide, physical properties, chemical properties

Physical and Chemical Properties of Nano Zinc Oxide Modified Asphalt Binder

Recently, nanotechnology has been used in all fields of science, including pavement engineering due to promising and improvement of materials offered. The modification of asphalt binder has evolved gradually, with several types of nanomaterials being employed to modify the asphalt binder. In this study, nano zinc oxide with flake structure was used as a modifier in asphalt binder. The nano modifiers were blended with penetration grade 60/70 asphalt binder at 3%, 5%, and 7%, respectively. Physical properties of the modified asphalt binders were then examined, including storage stability, penetration, softening point, and viscosity. Meanwhile, the chemical property was determined using Fourier-Transform Infrared Spectroscopy. It was discovered that 3% nano zinc oxide produced the best results. Nano zinc oxide was found not to show separation at high temperatures in a storage stability test. The addition of nano zinc oxide to the asphalt binder also reduced the penetration, increased the softening point, and reduced the viscosity. The high penetration index value also indicates that the asphalt binder treated with nano zinc oxide is thermally resistant.   Keywords: Nanotechnology, asphalt binder, nano zinc oxide, physical properties, chemical properties

Superheated steam treatment of oil palm mesocarp fiber improved the properties of fiber-polypropylene biocomposite

The effect of fiber surface modification by superheated steam (SHS) treatment and fiber content (30 to 50 wt.%) was evaluated relative to the mechanical, morphology, thermal, and water absorption properties of oil palm mesocarp fiber (OPMF)/polypropylene (PP) biocomposites. SHS treatment of OPMF was conducted between 190 and 230 C for 1 h, then the SHS-treated fiber was subjected to melt-blending with PP for biocomposite production. The biocomposite prepared from SHS-OPMF treated at 210 C with 30 wt.% fiber loading resulted in SHS-OPMF/PP biocomposites with a tensile strength of 20.5 MPa, 25% higher than untreated-OPMF/PP biocomposites. A significant reduction of water absorption by 31% and an improved thermal stability by 8% at T5%degradation were also recorded. Scanning electron microscopy images of fractured SHS-OPMF/PP biocomposites exhibited less fiber pull-out, indicating that SHS treatment improved interfacial adhesion between fiber and PP. The results demonstrated SHS treatment is an effective surface modification method for biocomposite production

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Rekabentuk dan prestasi antena MEMS penuai tenaga mikro frekuensi radio bagi peranti elektronik berkuasa rendah

Tenaga ambien Frekuensi Radio (RF) menjadi pilihan sebagai sumber tenaga hijau bagi sistem penuaian tenaga kerana kewujudan isyarat gelombang elektromagnetik yang sentiasa ada di persekitaran tanpa melibatkan kos. Tenaga RF ini adalah sangat rendah kebiasaannya kurang daripada 190 μW. Namun, antena perlu membekalkan kuasa yang mencukupi kepada sistem penuaian tenaga RF bagi menghidupkan peranti elektronik berkuasa rendah. Oleh itu, antena perlu direkabentuk bagi menangkap dan memindahkan tenaga kepada litar penuai tenaga mikro RF bagi membekalkan kuasa yang optimum kepada peranti elektronik tersebut. Rekabentuk antena mikrojalur menggunakan proses teknologi fabrikasi Mikro Elektro Mekanik (MEMS) adalah pilihan paling sesuai kerana bersaiz kecil, ringan dan berprestasi tinggi. Rekabentuk antena MEMS ini menggunakan perisian Computer Simulation Technology-Microwave-Studio (CST-MWS). Perbandingan telah dilakukan bagi empat jenis antena iaitu mikro-mesin permukaan silikon, mikro-mesin pukal silikon dengan rongga udara, mikro-mesin permukaan kaca dan RT/Duroid 5880 sebagai rujukan. Hasil simulasi menunjukkan antena mikro-mesin permukaan kaca bersaiz paling kecil berbanding tiga antena yang lain. Kehilangan balik antena ini juga adalah lebih baik iaitu meningkat sebanyak 55.1% dan 5.6% berbanding masing-masing, antena mikro-mesin permukaan silikon dan antena konvensional RT/Duroid. Antena ini juga mempunyai lebar jalur yang besar iaitu 117 MHz, gandaan melebihi 5 dB dan pengarahan melebihi 5 dBi. Antena mikro-mesin permukaan kaca telah berjaya difabrikasi menggunakan teknologi MEMS yang menghasilkan antena lutsinar bersaiz (L/W) 19 mm x 19 mm. Antena MEMS yang bersaiz kecil ini sangat sensitif dan sangat berkesan bagi menangkap isyarat ambien RF dan berkebolehan membekalkan kuasa yang mencukupi kepada sistem penuai tenaga RF

Investigation of Micromachined Antenna Substrates Operating at 5 GHz for RF Energy Harvesting Applications

This paper investigates micromachined antenna performance operating at 5 GHz for radio frequency (RF) energy harvesting applications by comparing different substrate materials and fabrication modes. The research aims to discover appropriate antenna designs that can be integrated with the rectifier circuit and fabricated in a CMOS (Complementary Metal-Oxide Semiconductor)-compatible process approach. Therefore, the investigation involves the comparison of three different micromachined antenna substrate materials, including micromachined Si surface, micromachined Si bulk with air gaps, and micromachined glass-surface antenna, as well as conventional RT/Duroid-5880 (Rogers Corp., Chandler, AZ, USA)-based antenna as the reference. The characteristics of the antennas have been analysed using CST-MWS (CST MICROWAVE STUDIO&#174;&#8212;High Frequency EM Simulation Tool). The results show that the Si-surface micromachined antenna does not meet the parameter requirement for RF antenna specification. However, by creating an air gap on the Si substrate using a micro-electromechanical system (MEMS) process, the antenna performance could be improved. On the other hand, the glass-based antenna presents a good S11 parameter, wide bandwidth, VSWR (Voltage Standing Wave Ratio) &#8804; 2, omnidirectional radiation pattern and acceptable maximum gain of &gt;5 dB. The measurement results on the fabricated glass-based antenna show good agreement with the simulation results. The study on the alternative antenna substrates and structures is especially useful for the development of integrated patch antennas for RF energy harvesting systems

Superheated Steam Treatment of Oil Palm Mesocarp Fiber Improved the Properties of Fiber-Polypropylene Biocomposite

The effect of fiber surface modification by superheated steam (SHS) treatment and fiber content (30 to 50 wt.%) was evaluated relative to the mechanical, morphology, thermal, and water absorption properties of oil palm mesocarp fiber (OPMF)/polypropylene (PP) biocomposites. SHS treatment of OPMF was conducted between 190 and 230 C for 1 h, then the SHS-treated fiber was subjected to melt-blending with PP for biocomposite production. The biocomposite prepared from SHS-OPMF treated at 210 C with 30 wt.% fiber loading resulted in SHS-OPMF/PP biocomposites with a tensile strength of 20.5 MPa, 25% higher than untreated-OPMF/PP biocomposites. A significant reduction of water absorption by 31% and an improved thermal stability by 8% at T5%degradation were also recorded. Scanning electron microscopy images of fractured SHS-OPMF/PP biocomposites exhibited less fiber pull-out, indicating that SHS treatment improved interfacial adhesion between fiber and PP. The results demonstrated SHS treatment is an effective surface modification method for biocomposite production