Radical polymerization of (phenylethynyl)styrenes and characterization of poly(phenylethynyl)styrenes as a thermally curable material

Summary The radical polymerizations of 2-, 3-, and 4-(phenylethynyl)styrenes (1a–c) and the copolymerizations of 1a–c (M₁) with styrene (M₂) were carried out using AIBN as the initiator in toluene at 60°C. The number-average molecular weights (M _ns) were extremely low for poly(2-phenylethynylstyrene) (2a) and poly[(phenylethynyl)styrene-co-styrene] (3a), and increased in the order of 2a, 3a << 2b, 3b < 2c, 3c. Monomer reactivity ratios were determined as r ₁= 1.80 and r ₂= 0.51 for 1a, r ₁= 1.72 and r ₂= 0.53 for 1b, and r ₁= 3.17 and r ₂= 0.24 for 1c. Polymers 2a–c and 3a–c underwent an exothermic reaction at elevated temperature to form organic solvent-insoluble polymers. Although the decomposition of 2a was observed from 200°C, 2b and 2c exhibited a high heat-resistance property in both nitrogen and air atmospheres, in particular, 2b showed no significant weight loss below 450°C. Received: 28 January 1998/Accepted: 5 March 1998     

Construction of self‐organizing algorithms for vector quantization

Vector quantization is used for both storage and transmission of speech and image data, and an algorithm that minimizes the distortion error is often required. To obtain the minimum distortion error in neural networks for vector quantization, corrective competitive learning has been introduced. In a large number of algorithms, self‐creating neural networks and self‐deleting neural networks have performed well. In this paper, we improve the self‐deleting neural network and propose a generalized algorithm combining the creating and deleting neural networks. First, a few weight (reference) vectors are prepared, the self‐creating algorithm is applied, and vectors are created automatically. Next, the self‐deleting algorithm is applied, and weight vectors are deleted sequentially to reach a predetermined number. Experimental results show the effectiveness of the proposed algorithm. © 1999 Scripta Technica, Electr Eng Jpn, 127(1): 47–55, 1999     

Proposal of cause–effect pattern library for realizing sustainable businesses

Sustainable business design has gained growing interest in recent years. However, it is often difficult to clarify which business activities actually contribute to (or violate) the sustainability of the earth due to high complexity of environmental and economical system of our society. In order to help a business to generate sustainable business ideas handling this complexity in a systematic and comprehensive manner, this paper proposes a method to formulate a wide variety of causalities in our society into a cause–effect pattern library and illustrates how to use it for design and planning of sustainable businesses.     

Effects of Tl-filling into the voids and Rh substitution for Co on the thermoelectric properties of CoSb3

In order to enhance the thermoelectric (TE) properties of CoSb₃, we tried to reduce the lattice thermal conductivity (κ_lat) by filling Tl into the voids and substitution of Rh for Co. We prepared polycrystalline samples of Tl_x(Co_1−yRh_y)₄Sb₁₂ (x = 0, 0.05, 0.10, 0.15, 0.20 and y = 0.1, 0.2) and examined their TE properties from room temperature to 750 K. All the samples indicated negative values of the Seebeck coefficient (S). Both the electrical resistivity and the absolute values of the S decreased with increasing the Tl-filling ratio. The Tl-filling and Rh substitution reduced the κ_lat, due to the rattling and the alloy scattering effects. The minimum value of the κ_lat was 1.54 W m⁻¹ K⁻¹ at 550 K obtained for Tl_0.20(Co_0.8Rh_0.2)₄Sb₁₂. Tl_0.20(Co_0.8Rh_0.2)₄Sb₁₂ exhibited the best TE performance; the maximum value for the dimensionless figure of merit ZT was 0.58 at around 600 K.     

Characterization of brighteners in detergents by high-performance liquid chromatography/mass spectrometry/ultraviolet/fluorescence and three-dimensional high-performance liquid chromatography

A method has been developed for the identification of unknown brighteners in detergents by a high-performance liquid chromatography (HPLC)/mass spectrometry (MS)/ultraviolet (UV)/fluorescence system with MS/MS capability. Ten brighteners from five groups—stilbene, biphenyl stilbene, pyrazoline, oxazole, and coumarin derivatives—were separated on a C₈ reverse-phase HPLC column. The UV and fluorescence detectors positively located the brightener peaks and differentiated betweentrans andcis isomers separated by the chromatographic system. Ion-spray (IS)/MS and IS/MS/MS spectra were then used to identify the structure of unknown brighteners in detergent products. An HPLC with a diode-array detector provided a quick identification check and accurate quantitative data for known brighteners, even on overlapping peaks.     

Product modularity for life cycle design

Modular design is an important elemental technique in life cycle design for improving, e.g., maintainability, upgradability, reusability, and recyclability. Appropriate modular structure differs according to applied life cycle options; e.g., while the modular structure for recycling should be based on material kinds, the structure for upgrading should be based on functions to be obsolete. This paper proposes a method for determining modular structure by aggregating various attributes related to a product life cycle and evaluating geometric feasibility of modules. This paper also illustrates the prototype system that implements the proposed method and a case study of a printer.     

Crystallization behavior of poly(l-lactic acid)

The crystallization behavior of poly(l-lactic acid) was studied in the range of 80-160 °C. The peak crystallization time (τ_p) was defined and obtained from the crystallization isotherm measured with a differential scanning calorimeter (DSC). Isothermal crystallization temperature (T_c) dependence of log(τ_p) discretely changed at 113 °C (= T_b). The linear growth rate of spherulite, G, was measured with a polarizing microscope. The T_c dependence of G and the size of the spherulite also discretely changed at T_b. Crystal structures for samples isothermally crystallized at temperatures which were higher and lower than T_b were orthorhombic (α-form) and trigonal (β-form), respectively. The discrete change of the crystallization behavior was explained by the formation of different crystal.     

Development of an optimal design aid system based on building information modeling

This study proposes an optimal building design aid system that integrates computer aided design (CAD), building environmental simulation tools and an optimization algorithm, based on the concept of building information modeling (BIM). BIM is a process of generating and managing data during a building’s life cycle. It can be used to demonstrate the entire building’s life cycle, including its construction and operation. Because the design of a build may vary from an abstract shape to precise details, the building’s database should vary accordingly. To store, manage and utilize the building’s data efficiently, we suggest an evolving database structure for our design aid system. A case study verifies that the system can acquire data from CAD, run a number of simulations and generate Pareto solutions automatically during several design stages.     

Optimization of variables in air conditioning control systems: Applications of simulations integrating CFD analysis and response factor method

The integration of three-dimensional spatial distributions into building simulations is of significant interest, and computational fluid dynamics (CFD) analysis is widely employed in building design processes. For example, based on the experience of architects and engineers, CFD analyses are often conducted under steady boundary conditions to determine the degree of attainment of indoor environments. However, CFD analyses have large calculation costs and cannot be often used for simulations with unsteady boundary conditions such as energy simulations in the building design processes. Thus, we developed a method that calculates sensitivities from heat sources to an arbitrary point in an indoor environment and integrates them into simulations with unsteady boundary conditions. In the proposed method, CFD analysis is employed under steady boundary conditions to calculate the response factors, and the resulting sensitivities are integrated into simulations under unsteady boundary conditions. In the present study, the proposed method was applied to optimize the variables of an air conditioning control system. With our method, temperature changes at a sensor over time are calculated from the time series of air supply temperature. In total, 800 calculations were conducted, and the optimal variables that allow the temperature at the sensor to reach the target value quickly were obtained. Except for the time required to calculate the response factors, the optimization in the present study took only a few seconds. If only CFD analysis was used for the optimization, the calculations would take a year. Thus, calculating the sensitivities via CFD analysis and utilizing the results in simulations is a useful approach for solving optimization problems. Moreover, the proposed method is applicable to simulations that require three-dimensional spatial distributions to enhance the accuracy of the calculation such as energy simulations.