Some basic but desirable employability skills are antecedents of job performance. The Workplace Skills Survey (WSS) is a 48-item situational judgment test (SJT) used to assess non-technical workplace skills for both entry-level and experienced workers. Unfortunately, the psychometric evidence for use of its scores is far from adequate. The purpose of current study was two-fold: (a) to examine the proposed structure of WSS scores using confirmatory factor analysis (CFA), and (b) to explore the WSS item functioning and performance using item response theory (IRT). A sample of 1,018 Jamaican unattached youth completed the WSS instrument as part of a longitudinal study on the efficacy of a youth development program in Jamaica. Three CFA models were tested for the construct validity of WSS scores. Parameter estimations of item difficulty, item discrimination, and examinee’s proficiency estimations were obtained with item response theory (IRT) and plotted in item characteristics curves (ICCs) and item information curves (IICs). Results showed that the WSS performed quite well as a whole and provided precise measurement especially for respondents at latent trait levels of -0.5 and +1.5. However, some modifications of some items were recommended. CFA analyses showed supportive evidence of the one-factor construct model, while the six-factor model and higher-order model were not achieved. Several directions for future research are suggested.

The diploma thesis focuses on laser welding of extra deep-drawn steel sheet according to the standard WSS-M1A365-A14 with a protective zinc surface layer. A 0,9 mm thick steel sheet with a zinc layer with coating weight 50 g · m^-2 is welded by a hybrid welding method Laser-TIG. The laser, as the primary energy source, is used for welding the material. The arc, provided by a non-melting tungsten electrode, is used for preheating the material for melting and evaporation of the zinc layer. Based on the initial experiments, the magnitude of the laser power with the welding speed was chosen as a constant parameter. The magnitude of the electric current, as the variable parameter, was set up to 0, 20, 30 and 40 ampers for welding the lap and the butt welds. Only one piece of the each weld type combination was made. The welds were afterwards tested to verify their quality and material properties. The first differences between laser welding with or without TIG preheating were visible during the experiment. The positive effects of the laser welding with preheating by TIG were confirmed. The material properties of the joints achieved better values and a influence of the welding defects on the quality of the joints was reduced. The Laser-TIG is a good choice for welding galvanized steel sheets in the mass production of automotive industry and it could be improved by more researches.

This thesis deals with description of human hearing, audio and speech codecs, description of objective measure of quality and practical comparison of codecs. Chapter about audio codecs consists of description of lossless codec FLAC and lossy codecs MP3 and Ogg Vorbis. In chapter about speech codecs is description of linear predictive coding and G.729 and OPUS codecs. Evaluation of quality consists of description of segmental signal-to- noise ratio and perceptual evaluation of quality – WSS and PESQ. Last chapter deals with description od practical part of this thesis, that is comparison of memory and time consumption of audio codecs and perceptual evaluation of speech codecs quality.

No description available.