Carbon assessment for cocoa cropping systems in Lampung, Indonesia

Cocoa (Theobroma cacao L.) production plays a key role in the economics of Indonesia, the world’s fourth largest cocoa bean producing country. With more than 1.6 million hectares of land planted with cocoa, small improvements in emissions efficiencies or carbon sequestration opportunities can have a relatively large mitigating effect on emissions from agroforestry and land use. The carbon assessment in Lampung, Sumatra was done to evaluate environmental impacts of cocoa as a commodity through estimation of carbon stock and carbon footprint, GHG emissions during the cultivation of cocoa in different cropping systems. Segmentation of cropping systems along density of intercropping, inputs use intensity and residue management practices identify opportunities for climate smart practices tailored to each segment

Bioconvection gravitactique dans un milieu stratifié

International audienceNous considérons le phénomène de bioconvection gravitactique dans une cavité rectangulaire poreuse saturée d'un fluide stratifié. La bioconvection est due aux mouvements ascendants des micro-organismes qui sont légèrement plus denses que l'eau, tandis que la stratification du fluide est d'origine solutal et joue un rôle stabilisant. Il sera montré que la bioconvection stationnaire dans un milieu stratifié est un phénomène d'instabilité sous-critique qui est due d'une part au mouvement gravitactique des micro-organismes, et d'autre part à la faible diffusivité des solutés par rapport à celle des micro-organismes. Il sera aussi montré qu'il existe un régime de bioconvection oscillante qui peut s'établir en-dessous du seuil critique du régime de bioconvection stationnaire

Effects of steel corrosion to BFRP Strengthened columns under eccentric loading

The experiment consists of twenty-four mid-scale rectangular RC columns (200x200x800mm) strengthening by BFRP sheets and research variables include: BFRP layer (0, 1, and 3 layers); eccentricity (25mm and 75mm); and 4 levels of steel corrosion. The results reveal that SEL (ratio of ultimate load of strengthened member to that of corresponding controlled member) is direct proportion with steel corrosion while SEV (ratio of ultimate vertical displacement of strengthened member to that of corresponding controlled member) is inverse proportion with steel corrosion; SEL slightly increases with the increase of BFRP layer and eccentricity; but SEV decreases noticeably with the increase of BFRP layer and eccentricity. In addition,the interaction between FRP sheets, stirrups, and longitudinal reinforcement in steel degraded BFRP strengthened columns is very strong.However, column design basing on current design manuals and codes as ACI 440.2R and CNR DT 200R1 has not mentioned this affect. Thus, the load capacity prediction of column being strengthened by BFRP sheets should include levels of steel corrosion for reality, reasonable, and integral of the design

Effects of steel corrosion to BFRP Strengthened columns under eccentric loading

The experiment consists of twenty-four mid-scale rectangular RC columns (200x200x800mm) strengthening by BFRP sheets and research variables include: BFRP layer (0, 1, and 3 layers); eccentricity (25mm and 75mm); and 4 levels of steel corrosion. The results reveal that SEL (ratio of ultimate load of strengthened member to that of corresponding controlled member) is direct proportion with steel corrosion while SEV (ratio of ultimate vertical displacement of strengthened member to that of corresponding controlled member) is inverse proportion with steel corrosion; SEL slightly increases with the increase of BFRP layer and eccentricity; but SEV decreases noticeably with the increase of BFRP layer and eccentricity. In addition,the interaction between FRP sheets, stirrups, and longitudinal reinforcement in steel degraded BFRP strengthened columns is very strong.However, column design basing on current design manuals and codes as ACI 440.2R and CNR DT 200R1 has not mentioned this affect. Thus, the load capacity prediction of column being strengthened by BFRP sheets should include levels of steel corrosion for reality, reasonable, and integral of the design

THE INFRASTRUCTURE AND ENVIRONMENT IN THE OLD TENEMENTS IN HANOI

Joint Research on Environmental Science and Technology for the Eart

Energy Lost in a Hydrogel Osmotic Engine Due to a Pressure Drop

Utilizing hydrogels to harvest salinity gradient energy from solutions of different salinities has recently attracted interest. Polyelectrolyte hydrogels exhibit cyclic swelling/deswelling when alternately exposed to freshwater and seawater. This can be utilized to convert the mixing energy of the two solutions into mechanical energy. Hydrogels consisting of a semi-interpenetrating network (semi-IPN) of poly(4-styrene sulfonic acid-co-maleic acid) sodium salt and polyacrylic acid was prepared at various cross-linking densities. The energy lost due to a pressure drop in the system during the deswelling/swelling process of these hydrogels is examined, and the effects of tubing dimensions, hydrogel cylinder size, gel particle size, and the volume fraction within the hydrogel cylinder occupied by the flowing liquid (ε) are investigated. In addition, a small-scale osmotic engine was compared to a scaled-up system. ε was found to be the factor that had the largest effect on the energy loss. It was found that ε is strongly dependent on the degree of swelling of the hydrogels. When the hydrogels swell, they deform more easily under pressure. This markedly decreases ε, thereby inducing a high pressure drop in the system and a correspondingly large energy loss. Accordingly, the pressure drop when pumping through the hydrogel is the major contributor to the energy loss in the system. When the hydrogel particles deform too much, the energy needed to pump the flowing liquid through the hydrogels exceeds the energy produced by the system. Developing a hydrogel system that deforms less in its swollen state is therefore essential for improving the energy efficiencies of these osmotic engines.publishedVersio

Design a cryptosystem using elliptic curves cryptography and Vigenère symmetry key

In this paper describes the basic idea of elliptic curve cryptography (ECC) as well as Vigenère symmetry key. Elliptic curve arithmetic can be used to develop elliptic curve coding schemes, including key exchange, encryption, and digital signature. The main attraction of elliptic curve cryptography compared to Rivest, Shamir, Adleman (RSA) is that it provides equivalent security for a smaller key size, which reduces processing costs. From the theorical basic, we proposed a cryptosystem using elliptic curves and Vigenère cryptography. We proposed and implemented our encryption algorithm in an integrated development environment named visual studio 2019 to design a safe, secure, and effective cryptosystem

An Overview of Cyanobacteria Harmful Algal Bloom (CyanoHAB) Issues in Freshwater Ecosystems

This chapter will present an overview of cyanobacterial harmful algal blooms (cyanoHABs) and biotic and abiotic factors, as well as various aspects associated with these worldwide ecological bursts. The exact causes of the cyanoHABs are still not well defined, but eutrophication and climate change (temperature increase, light intensity variation, etc.) are the two assumed main factors that may promote the proliferation and expansion of cyanobacterial blooms. However, these premises need to be profoundly investigated as the optimal combination of all factors such as increased nutrient loading, physiological characteristics of cyanobacterial species, and climate effects which could lead to the blooming pattern will require robust modeling approaches to predict the phenomena. Negative issues associated with cyanoHABs are diverse including the toxic products (cyanotoxins) released by certain taxa which can damage the health of humans and animal habitats around the related watershed as well as generate a huge water quality problem for aquatic industries