Effect of Soil Sulphur Levels on Feeding Preference of Brevicoryne brassicae on Brussels Sprouts

Two cultivars of Brussels sprouts, Brassica oleracea var. gemmifera were grown in pots treated with nutrient solutions containing five different levels of soil sulfur. Three replicates, each with 10 pots, were infested with the alate form of the aphid, Brevicoryne brassicae. Another three replicates were not infested with aphids. Total apterae aphids were counted on each leaf of the infested plants four weeks later. At the same time all plants were assayed for total glucosinolates and free thiocyanates. The greatest number of aphids per leaf on infested plants was found for the highest levels of sulfur applied. The highest concentrations of total glucosinolates were found in the leaves of uninfested plants that received the highest levels of sulfur. The lowest level of total glucosinolates was found in the leaves of infested plants that received the highest amount of sulfur, and these leaves had the highest level of free thiocyanates. The results suggest that aphids were attracted in greatest numbers to leaves that had the highest synthesis of glucosinolates and that their presence resulted in reduced glucosinolate levels by a combination of a depression in metabolic rate and a stimulation in myrosinase activity.     

Studying the sol-gel transition of styrene-divinyl benzene crosslinking co-polymerization via excimer forming dye molecules

A novel method based on the steady state fluorescence technique was used to study the sol-gel transition in the free radical crosslinking reaction between styrene (St) and divinyl benzene (DVB) with 2,2′-azobisisobutyronitrile (AIBN) as initiator. N-(4-(pyrenyl methylene)-oxycarbonyl phenyl)maleimide (Py-MI) was used as a fluorescence probe. The possible enchainment of Py-MI in alternating sequences occurred randomly in polymer clusters produced modifications in the fluorescence spectra, namely the shift at the higher wavelengths due to the excimer formation. The fluorescence spectra of Py-MI's excimers allowed both to monitor the sol-gel transition and to test the critical exponents as function of co-monomer's concentration. The gel fraction exponent β and the weight average degree of polymerization exponent γ agreed best with the static percolation values. Although this technique was applied for St-DVB co-polymerization, it may be generalized for the other monomers that are able to bind chemically to Py-MI monomer during the polymerization.     

Abrasive wear behaviour of SiC/2014 aluminium composite

Aluminium alloy matrix reinforced with 15 wt% SiC particles were prepared by powder metallurgy (PM) method. Wear behaviour of the composite was investigated to find out effects of operating variables and hardness in terms of the Taguchi approach, on a pin-on-disc machine and compared with the previous work on the composite produced by liquid metallurgy method [1]. Analysis of variance (ANOVA) was also employed to investigate which design parameters significantly affected the wear behaviour of the composite. The results showed that abrasive grain size exerted the greatest effect on the abrasive wear, followed by the hardness, which supported the previous work, but the percentage contribution was very different. The percentage contributions of the grain size and hardness were about 81.57 and 11.09, respectively. This might be because of production method of PM, particle size, model used by not considering the interaction effects, and testing condition. Moreover, larger particle sizes of the composites showed more wear resistance than those of others. As for the case of earlier work the percentage contributions of the grain size and type of material (hardness) were about 29.90, 17.90, respectively. However, the percentage contribution of interaction of abrasive size and hardness was about 30.90 while interaction of other factors was pooled.     

Fatigue life estimation of FBGA memory device under vibration

This paper predicts the fatigue life of fine-pitch ball grid array (FBGA) solder joints in memory devices due to harmonic excitation through experiments and finite element analysis. Finite element models of the memory device with simplified solder joints and with detailed solder joints were developed as a global model and a local model, respectively. A global-local modeling technique was used in the finite element simulation to calculate the stress magnitude of solder joints in the memory device under vibration. Stress versus life (S-N) curve was generated for the memory devices under various vibration levels to derive the fatigue constants of solder material. The fatigue life of the memory device was then determined by using the Basquin equation and Miner’s rule. It was experimentally verified that the predicted fatigue life of the memory device under cumulative damage conditions matches the experimental results within reasonable accuracy.     

Application of Taguchi methods in the optimization of cutting parameters for surface finish and hole diameter accuracy in dry drilling processes

The aim of the work reported here was to utilize Taguchi methods to optimize surface finish and hole diameter accuracy in the dry drilling of Al 2024 alloy. The parameters of hole quality are analyzed under varying cutting speeds (30, 45, and 60 m/min), feed rates (0.15, 0.20, and 0.25 mm/rev), depths of drilling (15 and 25 mm), and different drilling tools (uncoated and TiN- and TiAlN-coated) with a 118° point angle. This study included dry drilling with HSS twist drills. The settings of the drilling parameters were determined by using Taguchi’s experimental design method. Orthogonal arrays of Taguchi, the signal-to-noise (S/N) ratio, the analysis of variance (ANOVA), and regression analyses are employed to find the optimal levels and to analyze the effect of the drilling parameters on surface finish and hole diameter accuracy values. Confirmation tests with the optimal levels of machining parameters are carried out in order to illustrate the effectiveness of the Taguchi optimization method. The validity of Taguchi’s approach to process optimization is well established.     

On-line monitoring of flank wear in turning with multilayered feed-forward neural network

A multilayer feed-forward neural network (MLFF N-Network) algorithm is presented for on-line monitoring of tool wear in turning operations. The algorithm is based on the cutting conditions (cutting speed and feed rate) and measured cutting forces, which are used as inputs to a three-layer MLFF N-Network. The network is first trained using a set of workpiece material (P20 mold steel) and a tungsten carbide (H13A) cutting tool at various cutting conditions. The algorithm is later successfully verified on-line during turning of the same mold steel at conditions that differ from the data used in training. The algorithm is packaged in a software module, and integrated to an open Intelligent Machining Module used on industrial CNC systems.     

Economic and environmental impact of electric vehicles production in Indonesia

The use of fossil fuel-based vehicles may gradually be replaced by electric vehicles in the future. The trend indicates that the number of users of electric vehicles, especially electric cars, continues to increase. Indonesia is well-positioned to take advantage of this opportunity as it has the world’s largest nickel reserves, an essential raw material for making electric vehicle batteries (EVB). The study examines the economic and environmental implications if Indonesia were to successfully set up electric vehicle (EV) production rather than exporting such raw materials overseas. We use an input–output model to estimate electric vehicle production’s economic and environmental impacts in Indonesia. This study assumes that nickel, which is usually exported, is absorbed by domestic economic activities, including being used in manufacturing batteries and electric vehicles in Indonesia. Our estimates include direct and indirect output, value-added, and employment changes. The same model is also used to estimate changes in emissions’ environmental costs. It is evident from the results that batteries and EV production are economically beneficial. Additional value-added is Rp. 100.57 trillion, 1.5% of GDP in 2010. At the same time, 538,658 additional jobs were created, which is about a 0.5% increase. Lastly, EV production will have extra external costs of emissions, around Rp. 2.23 trillion, or an increase of about 0.6%. Based on these findings, it is concluded that electric vehicle production increases productivity, gross value-added, and job creation with a relatively small impact on the environment. A limitation of this study is that we assumed EVs were produced for export only, and we did not assume a reduction in economic activities in the supply chain of conventional vehicles.

Graphical Abstract

Economic and Environmental Impact of Electric Vehicles Production in Indonesia.

     

Time-dependent pressure-driven flow in a horizontal cylinder filled with a bidisperse porous material

Some properties of time-dependent that modify Brinkman equations for fluid flow in a cylindrical tube filled with Bidisperse Porous Material are discussed in this article. The fluid velocities through the fracture and porous phases of the Bidisperse Porous Medium (BDPM) resulting from the application of pressure gradient are described by two coupled second-order partial differential equations. Laplace transform technique, D'Alembert and Riemann-Sum Approximation Methods are used to obtain a semianalytical solution for the model. The choice of the D'Alembert is made to systematically decouple the coupled governing equations without altering their initial orders. The role of the coupling parameter: The coefficient of momentum transfer $(\eta )$ in the flow formation is considered. Accordingly, three cases are analyzed: (a) weak coupling $(\eta =0)$ which described the fluid flow in the absence of the coupling parameter, (b) the strong coupling resulting from a large value of the coupling parameter $(\eta \to \infty )$, and (c) fluid momentum for any arbitrary value of $\eta$. It is observed that fluid stability is attained when ${\mathit{Da}}_f$ and ${\mathit{Da}}_p$ are decreased; a finding that agrees with the findings of Nield and Kuznetsov and Magyari. Also, the maximum velocity in the fracture phase of the BDPM is attained when the coefficient of momentum transfer is neglected $(\eta =0)$ while an opposing flow formation is demonstrated in the fracture and porous phases of BDPM as $\eta$ is increased.