The status and prospects of in situ grain harvesting technology and its machine system

Two main types of in situ grain harvesttng machine are introduced. The comparison of their working principles and advantages are given. The limitations and prospects for stripper header are discussed.

Strategies for Household Water Supply Improvement with Rainwater Harvesting

There are significant household water supply challenges including quantity sufficiency and quality, which have economic and social implications. The challenges have remained despite the efforts of government establishing centralized or groundwater systems, and/or having individual crude systems. A Tanzanian rural household case study was considered by assessing the performance of a currently relied surface runoff collecting pond system for domestic purposes. A daily water balance model was applied with performance parameters, no water days (NWD) and rainwater usage (RUR). Rooftop runoff harvesting system was proposed as a water supply source in addition to the current one. Under such dual supply conditions, users can meet the drinking and non-drinking demand even in dry seasons at a minimum of 2 and 20 L/person/d, respectively. For rainwater harvesting adoption (considering selected regions), it was further established that amount and variation in rainfall impacts on quantity available for meeting demand. Increased catchment implies increased harvestable quantity, and with same storage higher reduction of number of NWD although with slight decrease of RUR. Also, increased storage is required for achieving higher RUR in case the same demand is maintained. But same storage can be maintained for increased demand relative to catchment size. However, rainwater catchment increase has greater impact on meeting a specified demand under given condition of rainfall quantity and variation. The RWH technology strategies presented in this study are replicable in other developing countries under site specific conditions.

Impact Assessment of Hillside Rainwater Harvesting Ponds on Agriculture Income: Case Study of Ntarama Sector in Rwanda

Nowadays, rainwater harvesting (RWH) technology is increasingly adopted as a strategic pathway for reducing poverty in rural drought prone areas for enhancing agricultural productivity and boosting farm income. The aim of this study is to assess the level of adoption and the impacts of RWH ponds on farm income in Ntarama sector of Bugesera District in Eastern Province of Rwanda. Fifteen farm ponds were visited and the level at which households adopted RWH ponds, their impact on farm income and performance in storing water were assessed. Interviews and questionnaires methods were used to farm ponds beneficiaries and the storage capacity of farm ponds was calculated to ensure that they meet irrigation water demand. Then, Microsoft excel was used as a data analysis tool. The results show that 42.5% of households have adopted RWH ponds and the adoption level of RWH ponds fails due to the lack of training about the role and use of RWH ponds before their implementation. Beside this the low level of public involvement during the site selection for ponds associated with social conflicts among water users was observed. However, it is further revealed that the use of RWH ponds positively impacts on agricultural income on 1/4 hectare per year by about 2,325,000 RWF (3100USD). The studied portion of area can bear 222 ponds of 120 m3 each if all the rain is harvested throughout the year instead of being three ponds. Furthermore, we found that the quantity of rainwater harvested of 328.5 m3 as a total of the 3 ponds was still too less to meet irrigation water demand. As negative impacts, the RWH technology can cause dangerous effects such as social conflicts, breeding site for mosquitoes, water related diseases, accidents and others with a level of severity of 32%, 24%, 20%, 16% and 8%, respectively. This happens when the RWH ponds are not properly managed.

Feasibility Demonstrations of Liquid Turbine Power Generator Driven by Low Temperature Heats

Lower temperature waste heats less than 373 K have strong potentials to supply additional energies because of their enormous quantities and ubiquity. Accordingly, reinforcement of power generations harvesting low temperature heats is one of the urgent tasks for the current generation in order to accomplish energy sustainability in the coming decades. In this study, a liquid turbine power generator driven by lower temperature heats below 373 K was proposed in the aim of expanding selectable options for harvesting low temperature waste heats less than 373 K. The proposing system was so simply that it was mainly composed of a liquid turbine, a liquid container with a biphasic medium of water and an underlying water-insoluble low-boiling-point medium in a liquid phase, a heating section for vaporization of the liquid and a cooling section for entropy discharge outside the system. Assumed power generating steps via the proposing liquid turbine power generator were as follows: step 1: the underlying low-boiling-point medium in a liquid phase was vaporized, step 2: the surfacing vapor bubbles of low-boiling-point medium accompanied the biphasic medium in their wakes, step 3: such high momentum flux by step 2 rotated the liquid turbine (i.e. power generation), step 4: the surfacing low-boiling-point medium vapor was gradually condensed into droplets, step 5: the low-boiling-point medium droplets were submerged to the underlying medium in a liquid phase. Experiments with a prototype liquid turbine power generator proved power generations in accordance with the assumed steps at a little higher than ordinary temperature. Increasing output voltage could be obtained with an increase in the cooling temperature among tested ranging from 294 to 296 K in contrast to normal thermal engines. Further improvements of the direct current voltage from the proposing liquid turbine power generator can be expected by means of far more vigorous multiphase flow induced by adding solid powders and theoretical optimizations of heat and mass transfers.

Cross-Layer Design for EH Systems with Finite Buffer Constraints

Energy harvesting(EH)technology in wireless communication is a promising approach to extend the lifetime of future wireless networks.A cross-layer optimal adaptation policy for a point-to-point energy harvesting(EH)wireless communication system with finite buffer constraints over a Rayleigh fading channel based on a Semi-Markov Decision Process(SMDP)is investigated.Most adaptation strategies in the literature are based on channeldependent adaptation.However,besides considering the channel,the state of the energy capacitor and the data buffer are also involved when proposing a dynamic modulation policy for EH wireless networks.Unlike the channeldependent policy,which is a physical layer-based optimization,the proposed cross-layer dynamic modulation policy is a guarantee to meet the overflow requirements of the upper layer by maximizing the throughput while optimizing the transmission power and minimizing the dropping packets.Based on the states of the channel conditions,data buffer,and energy capacitor,the scheduler selects a particular action corresponding to the selected modulation constellation.Moreover,the packets are modulated into symbols according to the selected modulation type to be ready for transmission over the Rayleigh fading channel.Simulations are used to test the performance of the proposed cross-layer policy scheme,which shows that it significantly outperforms the physical layer channel-dependent policy scheme in terms of throughput only.

Advanced ocean wave energy harvesting:current progress and future trends

With a transition towards clean and low-carbon renewable energy,against the backdrop of the fossil-energy crisis and rising pollution,ocean energy has been proposed as a significant possibility for mitigating climate change and energy shortages for its characteristics of clean,renewable,and abundant.The rapid development of energy harvesting technology has led to extensive applications of ocean wave energy,which,however,has faced certain challenges due to the low-frequency and unstable nature of ocean waves.This paper overviews the debut and development of ocean wave energy harvesting technology,and discusses the potential and application paradigm for energy harvesting in the“intelligent ocean.”We first describe for readers the mechanisms and applications of traditional wave energy converters,and then discuss current challenges in energy harvesting performance connected to the characteristics of ocean waves.Next,we summarize the progress in wave energy harvesting with a focus on advanced technologies(e.g.,data-driven design and optimization)and multifunctional energy materials(e.g.,triboelectric metamaterials),and finally propose recommendations for future development.