Modeling uncertainty of flexible structures with unknown high-order modal parameters - a geometric characterization of frequency responses

A control-oriented uncertainty modeling on frequency domain is presented for a class of spectral systems with unknown high-order modal parameters. At any user-specified frequency, the set of all the frequency responses of the feasible systems is characterized on a complex plane in terms of the convex bull of several circle segments, where the system is said to be feasible if partial modal parameters are given and some other conditions are satisfied by the unknown parameters. We emphasize that such a characterization enables us to quantify the least upper bounds of errors for any nominal models, and to develop further efficient results using some additional information. It is shown that, the DC gain information of the system reduces the size of the feasible set to the half or smaller for all frequencies. The efficiency of the presented scheme is demonstrated by a simple example of ideal flexible beam. </p

An optimal finite-dimensional modeling in heat conduction and diffusion equations with partially known eigenstructure

An optimal finite-dimensional modeling technique is presented for a standard class of distributed parameter systems for heat and diffusion equations. A finite-dimensional nominal model with minimum error bounds in frequency domain is established for spectral systems with partially known eigenvalues and eigenfunctions. The result is derived from a completely characterized geometric figure upon complex plane, of all the frequency responses of the systems that have (i) a finite number of given time constants T/sub i/'s and modal coefficients k/sub i/'s, (ii) an upper bound /spl rho/ to the infinite sum of the absolute values of all the modal coefficients k/sub i/'s, (iii) an upper bound T to the unknown T/sub i/'s, and (iv) a given dc gain G(0). Discussions are made on how each parameter mentioned above makes contribution to bounding error or uncertainty, and we stress that steady state analysis for dc input is used effectively in reduced order modeling and bounding errors. The feasibility of the presented scheme is demonstrated by a simple example of heat conduction in ideal copper rod. </p

Flexible equality: Men and women in employment in Japan

Changes in the structure and regulation of employment in Japan differentially impact men and women. The labor force participation of Japanese women is increasing, but women's employment is concentrated in relatively deregulated and flexible forms of non-standard and precarious employment. Women and men have relatively equal levels of unemployment at present, but the flexibility which characterizes part-time and temporary work lands women into the ranks of the unemployed throughout their life course, while men are more likely to experience unemployment at the entry and exit points to the labor market. Unemployment measures are directed mainly at alleviating the sources of male unemployment. Employment deregulation in Japan embodies varying degrees of re-regulation depending on the gender composition of work types. Part-time work is undertaken primarily by women, and remains relatively deregulated and unprotected. Temporary work regulations vary according to whether the occupations are typically performed by women (deregulated temporary work) or men (tightly regulated temporary work). Working hours have been deregulated for both men and women, but coupled with the deregulation of temporary work in female-dominated occupations, the change poses a greater disadvantage for women. The recent reform of the Equal Employment Opportunity Law in Japan, while responding in part to social demands for strengthening the regulation of equality, remains unenforceable. The analysis concludes that rather than more equality in employment, recent Japanese developments point to the institutional embedding of a gender segmented labor market, with men continuing in relatively protected and regulated standard employment and women relegated to flexible and deregulated employment. --employment,flexibility,regulation,labor,gender,Japan

Modeling flexible structures with unknown high-order modal parameters: a feasible set approach in frequency domain

A control-oriented uncertainty modeling on frequency domain is presented for a class of spectral systems with unknown high-order modal parameters. At any user-specified frequency, the set of all the feasible frequency responses is characterized on the complex plane where it is said to be feasible if partial modal parameters of a system are given and the other unknown modal parameters meet certain conditions. We emphasize that such a characterization enables us to quantify the least upper bounds of errors for any nominal models, and also to develop further efficient results using additional information. It is shown that the DC gain information of the system reduces the size of the feasible set to half or smaller one, for any frequencies. The efficiency of the presented scheme is demonstrated by a simple example of an ideal flexible beam. </p

The rise of temporary employment in Japan: legalisation and expansion of a non-regular employment form

"This discussion paper examines the institutionalization process of a non-regular employment form especially focusing on the establishment of the temporary dispatching work (haken) system. The institutionalization process of the haken system can be divided into three periods: delegalisation (1947-86), legalisation (1986-99), and diffusion (1999-). Declining labor strength, the emergence of deregulation bodies, and the changing attitude of the Ministry of Labor (MHLW) characterize the legal developments. Together with the liberalization of private job placement and the expansion of fixed-term contract work, temporary work became an important sources of flexible and skilled labor, and expanded more rapidly than other employment forms in the late 90s. In this development, temporary help firms started to reframe their business as 'personnel services,' and have positioned themselves to replace the traditional firm-internal supply of mobile employees such as shukkô and tenseki with external dispatched employees of temporary help firms." (author´s abstract

The rise of temporary employment in Japan: Legalisation and expansion of a non-regular employment form

This discussion paper examines the institutionalization process of a non-regular employment form especially focusing on the establishment of the temporary dispatching work (haken) system. The institutionalization process of the haken system can be divided into three periods: delegalisation (1947-86), legalisation (1986-99), and diffusion (1999-). Declining labor strength, the emergence of deregulation bodies, and the changing attitude of the Ministry of Labor (MHLW) characterize the legal developments. Together with the liberalization of private job placement and the expansion of fixed-term contract work, temporary work became an important sources of flexible and skilled labor, and expanded more rapidly than other employment forms in the late 90s. In this development, temporary help firms started to reframe their business as 'personnel services,' and have positioned themselves to replace the traditional firm-internal supply of mobile employees such as shukkô and tenseki with external dispatched employees of temporary help firms. --Japan,temporary work,non-regular employment,labor market,(de-)regulation

Modeling uncertainty for unknown modal parameters in large flexible structures

A procedure for control-oriented modeling is proposed for large flexible structures with unknown modal parameters. Techniques on quantification of errors in modal truncated nominal models are developed for the case where a finite number of upper and lower bounds of the unknown modal parameters are given. A feasible set of systems matching the conditions is introduced, and then error bounds covering the feasible set are established in the frequency domain. The bounds are easily checked using linear programming for any user-specified frequency. The feasibility of the proposed scheme is illustrated by numerical study on an ideal flexible beam example

Modeling uncertainty of large flexible structures with unknown modal parameters

A procedure for control-oriented modeling of uncertainty is proposed for large flexible structures. Techniques on quantification of errors in modal truncated nominal models are developed for the case where a finite number of upper and lower bounds of the unknown modal parameters are given. A feasible set of systems matching the conditions is introduced, and then error bounds covering the feasible set are established in the frequency domain. The bounds are easily checked using linear programming for any user-specified frequency. The feasibility of the proposed scheme is illustrated by numerical study on an ideal flexible beam example

The spatiokinematical structure of H_2O and OH masers in the "water fountain" source IRAS 18460-0151

Using the Very Long Baseline Array and the European VLBI Network, we have observed 22.2 GHz H_2O and 1612 MHz OH masers in the "water fountain" source IRAS 18460-0151. The H_2O maser spectrum has a very wide line-of-sight velocity range (~310 km/s) and consists of three groups of emission features at the blue-shifted (-68 km/s <~ V_LSR <~ -17 km/s) and red-shifted (V_LSR ~= 240 km/s) edges as well as around the systemic velocity (112 km/s <~ V_LSR <~ 133 km/s). The first two H_2O spectral components exhibit a highly-collimated high-velocity bipolar jet on the sky, with an angular separation of ~120 milliarcseconds (mas) (240 AU in linear length) and a three-dimensional flow velocity of ~160 km/s. The flow dynamical age is estimated to be only ~6 yr (at the time of the observation epochs of 2006--2007). Interestingly, the systemic velocity component clearly exhibits a spherically-expanding outflow with a radius of ~36 AU and a flow velocity of ~9 km/s. On the other hand, the OH maser spectrum shows double peaks with a velocity separation of ~25 km/s (V_LSR=$111--116 and 138--141 km/s), as typically seen in circumstellar envelopes of OH/IR stars. The angular offset between the velocity-integrated brightness peaks of the two high-velocity H_2O components is ~25 mas (50 AU). The offset direction and the alignment of the red-shifted maser spots are roughly perpendicular to the axis of the H_2O maser flow. High-accuracy astrometry for the H_2O and OH masers demonstrates that the collimated fast jet and the slowly expanding outflow originate from a single or multiple sources which are located within 15 mas (30 AU). On the other hand, the estimated systemic velocity of the collimated jet (V_sys ~87--113 km/s) has a large uncertainty. This makes it difficult to provide strong constraints on models of the central stellar system of IRAS 18460-0151.Comment: 25 pages, 5 figures, 8 tables, accepted for publication in Ap