A modified Lotka–Volterra model for competition forecasting in Taiwan’s retail industry

The retail industry is an important component of the supply chain of the goods and services that are consumed daily and competition has been increasing among retailers worldwide. Thus, forecasting the degree of retail competition has become an important issue. However, seasonal patterns and cycles in the level of retail activity dramatically reduce forecasting accuracy. This paper attempts to develop an improved forecasting methodology for retail industry competition subject to seasonal patterns and cycles. Using market share data and the moving average method, a modified Lotka–Volterra model with an additional constraint on the summation of market share is proposed. Furthermore, the mean absolute error is used to measure the forecasting accuracy of the market share. Real Taiwanese retail data from 1999 is used to validate the forecasting accuracy of our modified Lotka–Volterra model. Our methodology successfully mitigates errors from seasonal patterns and cycles and outperforms other benchmark models. These benchmarks include the Bass and Lotka–Volterra models for revenue or market share data, with or without using the moving average method. Our methodology assists the retail industry in the development of management strategies and the determination of investment timing. We also demonstrate how the Lotka–Volterra model can be used to forecast the degree of industry competition.     

Optical tomography hardware development for solid gas measurement using mixed projection

The ability to implement fan beam projection in parallel view in an optical tomography setup is one of the novelties of this research. This design involves a sensor jig specifically designed for parallel applications that does not involve a collimator. Therefore, the fan beam projections can also be implemented in the same sensor jig without difficulty. This method is a very practical solution for overcoming the disadvantages of parallel beam projection. Although the fan beam has its own disadvantages, combining the fan beam approach with the parallel beam approach is expected to further enhance the optical tomography image quality. The image quality can be measured using the Peak Signal-to-Noise Ratio (PSNR) and the Normalized Mean-Square Error (NMSE) parameters. The combination of the two approaches also eliminates the unwanted noise that appears when using parallel beam projection alone.     

Magnetic hierarchically porous biomass carbon for realizing broadband and strong absorption of electromagnetic wave

Hierarchically porous carbon materials provide favorable conditions for electromagnetic wave loss enhancement due to the superimposed positive influence of multilevel pores. However, high production costs and complex preparation limit their large-scale production. Biomass carbon with a natural hierarchically porous structure offers an alternative; however, the impedance mismatch and single-loss mechanism prevent biomass carbon from being an ideal absorbent for broadband and strong absorption. In this study, a series of magnetic hierarchically porous biomass carbons were prepared using a facile adsorption-inert calcination method. The natural hierarchical porous structure of the loofah sponge provides numerous adsorption sites for ferric ions, which are transformed in situ into Fe₃O₄ during calcination to regulate the conductivity. The impedance matching and electromagnetic loss properties of the biomass carbon/Fe₃O₄ composites were adjusted by varying the amount of ferric nitrate. Optimal performance occurs when ferric nitrate weighs 0.8 g, and the calcination temperature is 600 °C. Under these conditions, the effective absorption bandwidth reaches 5.28 GHz (11.84–17.12 GHz, 2.5 mm), and the minimum reflection loss (RL_min) is as low as −52.54 dB (4.5 mm), which is achieved by superior impedance matching and strong conduction loss together with polarization loss due heterogeneous interfaces and carbon defects. Our work provides a new perspective and a simple method for the large-scale production of high-efficiency biomass-based electromagnetic wave absorbents.     

Dual character of H2S as promoter and inhibitor for hydrodesulfurization of dibenzothiophene

Hydrodesulfurization (HDS) of dibenzothiophene (DBT) over laboratory synthesized bulk MoS₂ catalysts using batch microautoclave reactor was studied. Influence of H₂S (wide range level) on the DBT HDS activity and selectivity was investigated. In general, H₂S was found to inhibit the direct desulfurization route that leads to biphenyl regardless the catalyst applied. However, the hydrogenation pathway which mainly produces phenylcyclohexane inferred to be either uninhibited or even more interestingly highly promoted by the presence of H₂S depending on the catalyst nature. The ultimate sum impact of H₂S on the catalytic activity shows two extremes, inhibition and promotion. Mechanism of H₂S effect is proposed.     

GC–MS metabolomics revealed protocatechuic acid as a cytotoxic and apoptosis-inducing compound from black rice brans

Food Science and Biotechnology - GC–MS metabolomics was used to discriminate the phytochemicals profile of Indonesian white, red, and black rice brans, and Japanese white rice brans. This...     

Enhanced hydrogen-assisted cracking of 1,3,5-triisopropylbenzene over fibrous silica ZSM-5: Influence of co-surfactant during synthesis

In this study, unique fibrous silica ZSM-5 was successfully synthesized by using three type of alcohol possessing different alkyl-chain length as the co-surfactant. The effect of diverse co-surfactant was observed in the changes of physical properties, such as crystallinity, inter-dendrimer distances and pore properties. According to the IR and temperature programmed desorption of ammonia (NH₃-TPD) analyses, all catalysts exhibited different acid strengths which could be triggered by the different amount of additional silica species. All catalysts exhibited high catalytic performance in the hydrocracking of 1,3,5-triisopropylbenzene due to the absence of diffusion limitation. However, FZSM5C3 exhibited the highest catalytic activity which corresponded to its high number of Brønsted acid sites. It was observed that different length of co-surfactant alkyl-chain has resulted in different degree of oil penetration into the microemulsion system which subsequently triggered in various inter-dendrimer distances and amount of incorporated silica species. Hence, the altered physicochemical properties led to the difference in catalytic performance due to the presence of different number of Brønsted acid sites.     

An optimised low-salinity seawater decolourising method produces decolourised seaweed (Kappaphycuz alvarezii) as semi-refined carrageenan raw material:

Semi-refined carrageenan (SRC) production from decolourised Kappaphycuz alvarezii treated by chemicals (CaCO₃) drives the search for ‘greener’ decolourisation methods to sustainably supply cheaper and energy efficient products. Therefore, a decolourisation method of low-salinity seawater (LSS) (3, 9 and 15 g/L) was investigated to replace CaCO₃. In addition, decolourised seaweed colour powder (DSP) and SRC colour, yield, viscosity and gel strength were used to screen the salinity treatments. SRC prepared from LSS (3 g/L) treatment demonstrated similar colour and physical properties to CaCO₃ treatments, which indicated low-salinity seawater (3 g/L) could replace CaCO₃ as a decolourising agent. Moreover, purity of SRC (3 g/L salinity) were confirmed by x-ray diffraction (XRD), scanning electron microscopy-energy-dispersive x-ray (SEM-EDX), and its functional group by fourier transform infrared (FTIR). In this study, waste seawater from LSS (3 g/L) exhibited radical scavenging properties. This decolourising method could be easily adopted by smallholder seaweed farmers in low- and middle-income countries.     

Vanadium pentoxide film for microsecond pulse generation in 1.5-μm region

Q-switched erbium doped fiber laser (EDFL) was passively realized using vanadium pentoxide (V2O5) embedded into polyethylene glycol (PEG) film as saturable absorber (SA). The laser could successfully generate stable self-starting pulses when the V2O5 film was placed in an EDFL cavity. It operated at 1 562.4 nm wavelength. The repetition rate can be varied from 91.7 kHz to 128.2 kHz while the pulse width shrank from 10.90 μs to 7.81 μs with rising pump power from 110.9 mW to 166.5 mW. The pulse energy recorded was 3.2 nJ at pump power of 166.5 mW. The results indicate that the saturable absorption of V2O5 has promising nonlinear photonic applications especially in fiber laser development for 1.5-μm region.     

8-HQCdCl2H2O as an organic Q-switcher in erbium laser cavity

This paper demonstrated a Q-switched erbium-doped fiber laser (EDFL) using an organic saturable absorber (SA) based on 8-HQCdCl2H2O material. The organic thin film was prepared using the casting process. The proposed Q-switched EDFL has a maximum repetition rate of 143 kHz, minimum pulse duration of 1.85 µs and the highest pulse energy of 167 nJ. The Q-switched peak laser was at a central wavelength of 1 531 nm with a 3 dB bandwidth of 3.52 nm and power intensity of 2.64 dBm.