Beyond Alternative Text and tables: Comparative Analysis of Visualization Tools and Accessibility Methods

Modern visualization software and programming libraries have made data visualization construction easier for everyone. However, the extent of accessibility design they support for blind and low-vision people is relatively unknown. It is also unclear how they can improve chart content accessibility beyond conventional alternative text and data tables. To address these issues, we examined the current accessibility features in popular visualization tools, revealing limited support for the standard accessibility methods and scarce support for chart content exploration. Next, we investigate two promising accessibility approaches that provide off-the-shelf solutions for chart content accessibility: structured navigation and conversational interaction. We present a comparative evaluation study and discuss what to consider when incorporating them into visualization tools.     

A preliminary conceptual design study for Korean fusion DEMO reactor

As the ITER is being constructed, there is a growing anticipation for an earlier realization of fusion energy, so called fast-track approach. Korean strategy for fusion energy can be regarded as a fast-track approach and one special concept discussed in this paper is a two-stage development plan. At first, a steady-state Korean DEMO Reactor (K-DEMO) is designed not only to demonstrate a net electricity generation and a self-sustained tritium cycle, but also to be used as a component test facility. Then, at its second stage, a major upgrade is carried out by replacing in-vessel components in order to show a net electric generation on the order of 300 MWe and the competitiveness in cost of electricity (COE). The major radius is designed to be just below 6.5 m, considering practical engineering feasibilities. By using high performance Nb₃Sn-based superconducting cable currently available, high magnetic field at the plasma center above 8 T can be achieved. A design concept for TF magnets and radial builds for the K-DEMO considering a vertical maintenance scheme, are presented together with preliminary design parameters.     

A mathematical study on a unified variational principle with two constrained parameters

In this paper, a parameterized variational principle based on a mixed functional obtained by a linear combination of the total potential energy functional, the modified Hellinger-Reissner functional, and the Hu-Washizu functional with two constrained parameters is proposed, and the mathematical characteristics of the variational equation of the principle are investigated for the analysis of boundary value problems in linear elasticity. It is first proved that the Euler-Lagrange equations of the variational equation is identical to the governing equations for the given problem. Then existence of the unique solution of the variational equation is systematically proved by showing that the energy bilinear form is weakly-coercive. As an application, the stress/strain smoothing can be obtained as a form of mixed FEM based on the variational equation.     

Experimental study of miniaturized tip test

A tip test was developed and used successfully for friction measurement between the billet and dies or punches for the cold forging process. In the present investigation, the test was downsized and experimentally investigated to find the size effect on test results. For the test, aluminum alloys of 2024-O and 6061-O were used and the specimen was made into a cylinder of diameter and height of 10.0mm and 5.0mm, respectively. For lubrications, VG32, VG100, grease, and corn oil were used in experiments and tests were also carried out with two different humidity conditions. A micro-hardness test was made to compare the hardness distribution with the strain distribution obtained from the finite element simulation. The load levels and tip distances were measured for Al6061-O specimen with various lubrication conditions and compared to each other to find any correlation between the two. The shear friction factors were determined for various lubrications by using the finite element simulation under the present condition.     

Treatment of strong nitrogen swine wastewater in a full-scale sequencing batch reactor.

Treatment of swine wastewater containing strong nitrogen was attempted in a full-scale SBR. The strongest swine wastewater was discharged from a slurry-type barn and called swine-slurry wastewater (SSW). Slightly weaker wastewater was produced from a scraper-type barn and called swine-urine wastewater (SUW). TCOD, NH4+-N and TSS in raw SSW were 23,000-72,000 mg/L, 3,500-6,000 mg/L and 17,000-50,000 mg/L, respectively. A whole cycle of SBR consists of 4 sub-cycles with anoxic period of 1 hr and aerobic period of 3 hr. The maximum loading rates of both digested-SSW and SUW were similar to 0.22 kg NH4+-N/m3/day whereas the maximum loading rates of raw SSW was up to 0.35 TN/m3/day on keeping the effluent quality of 60 TN mg/l. The VFAs portion of SCOD in raw SSW was about more than 60%. The VFAs in SUW and digested-SSW were about 22% and 15%, respectively. NH4+-N and PO4(3-)-P in SSW were removed efficiently compared to those in digested-SSW and DUW because SSW had high a C/N ratio and readily biodegradable organic. High concentration of organic was useful to enhance denitrification and P uptake. Also the amount of external carbon for denitrification was reduced to 5% and 10% of those for digested-SSW and SUW.     

Optimal design of composite hood with reinforcing ribs through stiffness analysis

Fiber glass reinforced composites like sheet molding compounds (SMC) have recently been widely used in the fabrication of two-piece automobile hoods for passenger cars. In the present investigation, a one-piece composite hood with reinforcing ribs was optimally designed and manufactured by resin transfer molding in order to reduce manufacturing cost. In order to obtain the optimal design, stiffness analyses for deflections due to self-weight, oil canning, and torsion test conditions were carried out by applying the ABAQUS/Standard program. Based on these analyses, the thickness dimension of the composite hood required to maintain a stiffness comparable to a conventional steel hood was determined. For optimization studies of the weight reduction of the currently proposed one-piece composite hood with reinforcing ribs, IDESIGN program was employed. Based on a recursive quadratic programming technique, the thickness dimensions of the reinforcing ribs were optimized. The deflection ratios between fiber glass reinforced composite and conventional steel hoods were minimized in the optimization studies. From the present studies, it was found that the weight saving effect obtained by introducing the optimally designed one-piece composite hood was 37% compared to the conventional steel hood. This ranged approximately from 30 to 40% for composite hoods manufactured by resin transfer molding, depending on the composite materials used. Through these studies, it was confirmed that the one-piece composite hood was a preferable design and manufacture, compared to currently used composite hood made in two pieces, in terms of weight reductions and manufacturing cost without losing the stiffness required.     

Effects of morphologies of (Cd+Te) powders on the properties of sintered CdS/CdTe solar cells

Polycrystalline CdS/CdTe solar cells have been prepared by coating and sintering a CdS slurry and a (Cd+Te) slurry. CdS layers were first formed on borosilicate glass substrates at 600°C in nitrogen and then CdTe layers were formed on the sintered CdS layers at 625°C in nitrogen. The (Cd+Te) slurry contained (Cd+Te) powders mixed in a ball mill for 12–220 h instead of more expensive CdTe powders. The shape of cadmium particles changed from spherical to plate-like and the diameter of the plate-shaped particles became smaller as the ball-milling time increased. In addition, a compound CdTe started to form during a long milling time. The sintered CdTe layers were more compact as the diameter of plate-shaped cadmium particles decreased. However, cracks developed in the sintered CdTe layer when the diameter was small ( 2 m). The efficiency of sintered CdS/CdTe solar cells increased with decreasing particle diameter and then decreased with further decrease in particle diameter. The highest efficiency of 12.1% was achieved using a mixture of (Cd+Te) powders which had plate-shaped cadmium particles with a diameter of 5 m. The results suggest that high-efficiency sintered CdS/CdTe solar cells can be fabricated by using CdTe slurry from the mixture of (Cd+Te) powders with an inexpensive ball-milling process.     

Effects of junction formation conditions on the photovoltaic properties of sintered CdS/CdTe solar cells

Microstructures and properties of sintered CdS films on glass substrates and sintered CdTe films on polycrystal CdS substrates have been investigated. The CdS films, which contained 9 wt % CdCl₂ as a sintering aid and were sintered at 650° C for 1 h in nitrogen, are transparent and have an average grain size of 15m and an electrical resistivity of 0.5cm. The CdTe films, which were coated on the sintered CdS substrate and were sintered above 610° C for 1 h in nitrogen, have a dense structure with an average grain size larger than 5m. All polycrystal CdS/CdTe solar cells were fabricated by this successive coating and sintering method. The sintering temperature of CdTe films on the sintered CdS films was varied from 585 to 700° C. Compositional interfaces and p-n juctions are formed during sintering. The highest solar efficiency (7.18%) was found in a solar cell made by sintering the composite layer of glass-CdS-CdTe at 625° C for 1 h. A fabrication temperature below 610° C resulted in poor solar cell efficiencies due to the porous structure of the CdTe films and above 650° C also resulted in poor efficiencies due to the formation of a CdS_1-x Te_x layer at the interface and a large p-n junction depth.     

Optical and Magnetic Properties of Ten-Period InGaMnAs/GaAs Quantum Wells

Ten layers of InGaMnAs/GaAs multiquantum wells (MQWs) structure were grown on high resistivity (100) p-type GaAs substrates by molecular beam epitaxy (MBE). A presence of the ferromagnetic structure was confirmed in the InGaMnAs/GaAs MQWs structure, and have ferromagnetic ordering with a Curie temperature, T _C=50 K. It is likely that the ferromagnetic exchange coupling of the sample with T _C=50 K is hole-mediated resulting in Mn substituting In or Ga sites. PL emission spectra of the InGaMnAs MQWs sample grown at a temperature of 170 °C show that an activation energy of the Mn ion on the first quantum confinement level in InGaAs QW is 32 meV and impurity Mn is partly ionized. The fact that the activation energy of 32 meV of Mn ion in the QW is lower than an activation energy of 110 meV for a substitutional Mn impurity in GaAs, indicating an impurity band existing in the bandgap due to substitutional Mn ions.