Effect of coupling agent content on properties of composites made from polylactic acid and chrysanthemum waste

Chrysanthemum flower is among one of the highly sought after and widely planted flower crops, in particular for cultural and religious ceremonies. However, the chrysanthemum stem and stalk have little value and usually discard as by‐product waste from floristry. The objective of this research is to investigate the potential value of utilizing chrysanthemum stem and stalk as reinforcing fillers for thermoplastic composites. In this study, 2‐mm thick composite sheet containing predefined formulations of polylactic acid (PLA), chrysanthemum waste filler (CWF) ranging from 15 to 60 phr, and maleated polyethylene (MAPE) coupling agent up to 5 phr were prepared with the aid of Haake internal mixer and compression molding. The effect of MAPE loading on tensile, thermal, and morphological properties of PLA/CWF composites was investigated. The findings revealed that PLA/CWF composite attained improved tensile modulus compared to the neat PLA, and the tensile modulus increases with higher concentration of CWF. However, both tensile strength and elongation at break reduces with increase loading of CWF. Overall, PLA/CWF composites with MAPE shows better performance compared to those without MAPE, where an optimum strength of 21.8 MPa can be achieved with 60 phr CW and 3 phr MAPE. The measured tensile strength is comparable to alternatives natural fiber thermoplastic composites demonstrating its potential to be used in non‐structurally demanding application. J. VINYL ADDIT. TECHNOL., 26:10–16, 2020. © 2019 Society of Plastics Engineers     

Efficient performance analysis of asynchronous cellular CDMA overRayleigh-fading channels

The bit error rate (BER) analysis of a direct-sequence code-division multiple-access (DS-CDMA) cellular system over a Rayleigh-fading channel often results in complicated expressions even though the Gaussian approximation is applied. A combined probability density function (pdf) approach for the forward link and a mean-method technique for the reverse link are proposed to significantly reduce the computational complexity. The simplified BER expressions are derived and yield accurate results     

Selective hydrogenation of oleic acid to 9-octadecen-1-ol: Catalyst preparation and optimum reaction conditions

A new catalyst, ruthenium-tin-alumina is found to selectively hydrogenate oleic acid to 9-octadecen-1-ol (oleyl + elaidyl alcohol) at low pressure with high yield. Catalyst preparation methods, catalyst raw materials and activation conditions have a significant effect on the activity of the catalyst. The optimum atomic ratio of ruthenium to tin is about 1:2. Catalyst prepared by an improved sol-gel method shows higher activity and selectivity than catalysts prepared by impregnation and coprecipitation methods. Chloride is found to have a negative effect on catalytic activity. The best catalyst is prepared from chloride-free ruthenium and tin raw materials. Under the optimum reaction conditions of 250°C and 5.6 MPa, the selectivities for 9-octadecen-1-ol and total alcohol (9-octadecen-1-ol + stearyl alcohol) formation are 80.9% and 97%, respectively, at a conversion of 81.3%.     

Variations in meat quality in live halothane heterozygotes identified by biopsy samples of M. longissimus dorsi

The meat quality of halothane heterozygotes (Nn) was investigated using British Landrace (n = 18) and Landrace × Large White pigs (n = 67). Normal and PSE meat were identified in both breeds using M. longissimus dorsi (LD). In Landrace × Large White Nn pigs, the potential meat quality identified using small biopsy LD samples (500 mg) showed a wide spectrum in water-holding capacity (WHC), ranging from normal (43%) to PSE (57%). Predictions of meat quality in live pigs were confirmed from post-mortem assessments of LD samples based on pH(1) and fibre optic probe measurements. Our results show that Nn pigs have the propensity to produce a higher proportion of PSE than normal carcasses. The predictive meat quality test performed on small biopsy LD samples offers an opportunity not currently available to the pig industry, to select Nn pigs with the potential to produce pork of superior WHC.     

Measuring hydraulic properties of geotextiles after installation damage

Since geotextiles have been progressively incorporated into coastal protection structures, the influence of installation damage on them has been the primary concern. During installation/construction, geotextiles are repeatedly subjected to high mechanical stresses which often exceed service stress. It is therefore vital to evaluate the mechanical and hydraulic damage and determine the consequences of these damages to better develop criteria for selection of suitable products. As these damages could reduce the material's mechanical strength and hydraulic efficiency, or in the severest form of damage, puncturing, would end the separation function. The properties investigated in this paper include the permittivity and apparent opening size (AOS) of geotextiles. Generally, the greater the drop energy of armour units applied to geotextiles, the greater the potential for damage. Findings show that the residual permittivity could increase significantly, 45% during installation. The preliminary design of coastal structures will be optimised as engineers and designers can better estimate the amount of damage on geotextiles upon installation.     

Patterns of email use by teachers and implications: A Singapore experience

This paper attempts to identify the patterns of email use by schoolteachers. The findings are based on a survey of 2998 Singapore teachers whose teaching experiences ranged from 24 to 48 months. The result shows that teachers use email mainly to communicate with colleagues, and the degree of email use varies according to the school level that the teachers are working in. While the teachers teaching at higher school levels (Grades 11–12) email their colleagues more frequently than their counterparts teaching at lower school levels especially primary school teachers, the latter tend to email parents more frequently than other teachers. Implications of the findings are discussed in relevance to pre-service teacher education, teacher professional development and ICT adoption in organisations.     

Fundamental Analysis of Profitability of Large Engineering and Construction Firms

This research examines the strategic performance of sixty-one large international engineering and construction (E&C) firms from the regions of North America, Europe, and East Asia. The primary objective is to identify critical factors of corporate strategy that potentially affect the prospects of a large E&C firm. The research methodology relies on financial analysis and strategic management theories to draw meaningful conclusions. Statistical tests are selectively conducted to assess various aspects, including profitability, capital structure and asset liquidity. This paper documents the research findings for the first aspect—profitability. The first part of the findings suggests that there is no significant correlation between firm size and profitability. Large firms, which are endowed with greater resources and prowess, are not guaranteed to be more profitable. However, firm size has some influence on generic strategies, as large firms tend to adopt either a broadly targeted or a nonrelated diversification strategy. Regional trends of revenue growth of firms are subsequently presented. Despite strong forces of globalization experienced in many other industries, the growth trends suggest that the construction business remains largely localized in nature. Consequently, domestic and regional economic outlook, rather than global trends, should be given more weights in strategic planning.     

Robustness of time‐scale learning of robot motions to uncertainty in acquired knowledge

A disadvantage of present iterative learning control algorithms is that they are generally applicable only in cases where a certain task is performed over and over again. Consequently, if knowledge or control inputs acquired from learning a task can be used on similar tasks, learning will be more efficient. Recently, several methods for constructing the control input of a new motion based on the control inputs acquired from previous learning of similar tasks have been proposed. However, these methods assumed that the perfect control inputs could be obtained from the previous learning. In practice, the control inputs could never be obtained exactly from learning in the presence of certain uncertainties such as disturbance and measurement noises. In addition, it is also not known for sure how the basic motion patterns should be chosen for learning. In this article, the robustness problem of the time‐scale learning control to uncertainty in the acquired learning control inputs is formulated and solved. From the analysis, certain new insights such as its implication to choices of basic motion patterns for time‐scale learning will be discussed. Simulation results of a 3‐link robot are presented to illustrate the analysis. © 2001 John Wiley & Sons, Inc.     

High yield luminescence of a novel europium complex by excimer excitation and f–f absorption of Eu

A new organic ligand, 2-allyl-1,3-diphenyl-1,3-propanedione (ADP), and the corresponding quaternary Eu³⁺ complex, bi (ADP) (dibenzoyl methane) (1,10-phenanthroline) europium(III) [Eu(ADP)₂(DBM)(Phen)] have been synthesized. Excellent red luminescence from the Eu³⁺ complex was observed excited at 419 nm, and the broad visible excitation band is attributed to excimer absorption. The luminescence quantum yield excited at 419 nm (34 ± 3%) was higher than that at 380 nm (30 ± 3%). This is the first time to find strong and high yield excimer excitation absorption for a europium complex at room temperature, therefore, the excimer absorption band located in visible region (400–500 nm). Moreover, very high yields of direct f–f excitation absorption of Eu³⁺ ions at 466 nm (104 ± 10%) and 536 nm (96 ± 10%) were firstly observed, and the excitation spectrum for the europium complex in solid state is extended in wide region from 220 nm to 580 nm.