زينب شاكر رديف الدليمي

Enhancing the performance of nanogenerators is vital in the development of new piezoelectric applications that reveal high sensitivity to the surrounding waste of mechanical vibrational energy. In this paper, two major solutions are presented. The first is an easy and low-cost nanogenerator method utilizing Disodium Hexatitanate (Na2Ti6O13) as an alkali catalyzed material for growing the ZnO seed layer. The second solution is to suppress the screening effect that takes place in ZnO-metal harvester by forming a ZnO–Na2Ti6O13 heterojunction harvester. In other words, improvement can be realized by adopting a p-n junction approach instead of using the traditional Schottky contact approach. The ZnO–Na2Ti6O13 nanogenerator was grown hydrothermally. The size and nanofiber's shape, material compounds distribution in the p-n junction and the crystal phases are investigated. The result was a fabricated ZnO nanofiber with a length and diameter of 3.726 μm and 0.158 μm respectively and the average crystal size of the Na2Ti6O13 nanofiber was 97.74 nm, with a fiber diameter of approximately 8.699 nm. The maximum AC voltage (Vpk-pk) and current upon finger pressing reached about 2 V and 2 μAcm−2 respectively. A good rectification property resulted based on the use of a p-n junction approach. The ZnO–NTO nanofiber could provide DC voltage up to 3.6 V where the derived energy is sufficient to power LCD digital screen.

This article investigates the effect of structural dynamics on voltage generation from a novel dual coupled cantilever based piezoelectric vibration energy harvester (PVEH) system. Two non-destructive vibration techniques using the EMA and ODS analysis techniques have been integrated into the location selection scheme for enhancing vibration energy harvesting purpose. The location selection scheme is based on a measurement procedure on both harvester and its host structure to identify the optimal location. The results shows that the proposed cantilever PVEH is able to harvest high voltage in the high displacement region. An optimal location, (i.e. maximum vibration points/anti-nodal points) determined by the location selection scheme could yield 33.3% improvement in harvested voltage, as compared to baseline voltage. Meanwhile, if the piezoelectric plate is placed at any minimal vibration points or nodal point on the structure as determined by the location selection scheme, a significant reduction (>70%) in harvested voltage is observed.

Abstract: Recently, piezoelectric materials have achieved remarkable attention for charging wireless sensor nodes. Among piezoelectric materials, non-ferroelectric materials are more cost effective because they can be prepared without a polarization process. In this study, a non-ferroelectric nanogenerator was manufactured from 0.7PbZn0.3Ti0.7O3-0.3Na2TiO3 (PZnT-NT). It was demonstrated that the increment of conductivity via adding the Na2TiO3 plays an essential role in increasing the permittivity of the non-ferroelectric nanogenerator and hence improved the generated power density. The dielectric measurements of this material demonstrated high conductivity that quenched the polarization phase. The performance of the device was studied experimentally over a cantilever test rig; the vibrating cantilever (0.4 ms−2) was excited by a motor operated at 30 Hz. The generated power successfully illuminated a light emitting diode (LED). The PZnT-NT nanogenerator produced a volume power density of 0.10 μw/mm3 and a surface power density of 10 μw/cm2. The performance of the proposed device with a size of (20 × 15 × 1 mm3) was higher in terms of power output than that of the commercial microfiber composite (MFC) (80 × 57 × 0.335 mm3) and piezoelectric bimorph device (70 × 50 × 0.7 mm3). Compared to other existing ferroelectric and non-ferroelectric nanogenerators, the proposed device demonstrated great performance in harvesting the energy at low acceleration and in a low frequency environment.

التنظيم الإداري وبيروقراطية التنفيذ دون تحقيق الشفافية المطلوبة للمحاسبة والمساءلة في ضوء رقابة شعبية اي إن دور المعلوماتية هو خلق بيئة تفاعلية بين صانعي القرار وعموم المجتمع كونه المتأثر بقرارات السلطات التنظيمية العليا.ان التعرف على إمكانية مساهمة تقنية المعلومات في أتمتة النظم الإدارية في جامعة الكوفة من خلال دراسة تأثرها بمكونات البيئة الإدارية والمجتمعية والمادية باتت ضرورة تساهم في وضع التوصيف الدقيق لإلية التطبيق وتوظيف التنظيم المعلوماتي. ان منهجية البحث اعتمدت الطرق الاستبيانية لرصد مستوى الأداء الإداري ومستوى تأهيل الموارد المادية والمجتمعية للمضي قدما نحو تفعيل الأنظمة الإدارية الالكتروني بصيغتها الحديثة وتختتم الدراسة بتوصيات ومقترحات يؤمل مساهمتها في تفعيل دور تقنية المعلومات و رفع كفاءة وفاعلية النظم الإدارية.

Recently, environmental preservation issues have been critical between the chemical pollution matters and the development technology requirements. However, the renewable and friendly materials come to use. Numerous researches have richly studies the natural fiber reinforcement polymer composites. This fact, based on both fibers and matrixes are derived from renewable resources. Therefore, the formed composites have more compatibility with the environmental preservation issues. [1] Isabel investigated of the most natural fibers are used such as palm, cotton, silk, coconut, wool and wood fibers. A significant development in the lignocelluloses fiber in thermoplastics realized the distinct researches presented by [2-5] Composite-reinforcing fibers can be categorized by chemical composition, structural morphology, and commercial function. Natural fibers, such as kenaf, ramie, jute, flax, sisal, sun hemp and coir are derived from plants that used almost exclusively in PMCs. Aramid fibers[6] are crystalline polymer fibersare mostly used to reinforce PMCs. The compounds percentage of composite have the essential role for verify the designed values according to applications, therefore the mechanical properties of PMCs predicated by Mohamed (2007).

The fracture behaviour represents the most critical issue in the automotive and aerospace engine fields. Thus, the objective of this study was to estimate and analyze the crack criteria by using the Mathematical laws that were limited in E 1820 standard and the results affirmed by applying the numerical solutions of ANSYS to estimate the fracture toughness value KIC, besides the energy release rate of biomass composite. The specimens were prepared from different percentage of kenaf mat (KM) and unsaturated polyester resin (UP) 20% KM – 80% UP and 40% KM – 60% UP, respectively, as well the other composite properties which were calculated using the stress-strain data. The fracture characterizations of this composite were carried out using the compact tension (CT) specimen that was commonly used to determine Mode-I fracture properties. The fracture toughness has been found to be independent of pre-crack length. Meanwhile, the tests were performed at room temperature. The numerical simulations of the ANSYS model results demonstrated a good agreement between the experiments computed results of the fracture toughness. The fracture toughness KIC of 20% KM – 80% UP and 40% KM – 60% UP was equivalent to 0.76 MPa√m and 2.0 MPa√m, respectively. Thus, the fracture propagation is dependent on the fibre percentage of the composite. On the other hand, there are unlimited mechanisms of crack paths derived from randomly kenaf mat packs, particularly in the frontal process zone of crack tip.