Error Modelling and Experimental Validation of a Planar 3-PPR Parallel Manipulator with Joint Clearances

International audienceThis paper deals with the error modelling and analysis of a 3-\underline{P}PR planar parallel manipulator with joint clearances. The kinematics and the Cartesian workspace of the manipulator are analyzed. An error model is established with considerations of both configuration errors and joint clearances. Using this model, the upper bounds and distributions of the pose errors for this manipulator are established. The results are compared with experimental measurements and show the effectiveness of the error prediction model

Interaction model for magnetic holes in a ferrofluid layer

Nonmagnetic spheres confined in a ferrofluid layer (magnetic holes) present dipolar interactions when an external magnetic field is exerted. The interaction potential of a microsphere pair is derived analytically, with a precise care for the boundary conditions along the glass plates confining the system. Considering external fields consisting of a constant normal component and a high frequency rotating in-plane component, this interaction potential is averaged over time to exhibit the average interparticular forces acting when the imposed frequency exceeds the inverse of the viscous relaxation time of the system. The existence of an equilibrium configuration without contact between the particles is demonstrated for a whole range of exciting fields, and the equilibrium separation distance depending on the structure of the external field is established. The stability of the system under out-of-plane buckling is also studied. The dynamics of such a particle pair is simulated and validated by experiments.Comment: 15 pages, 11 figures (18 with subfigures). to appear in Phys. Rev.

Planet Occurrence within 0.25 AU of Solar-type Stars from Kepler

We report the distribution of planets as a function of planet radius (R_p), orbital period (P), and stellar effective temperature (Teff) for P < 50 day orbits around GK stars. These results are based on the 1,235 planets (formally "planet candidates") from the Kepler mission that include a nearly complete set of detected planets as small as 2 Earth radii (Re). For each of the 156,000 target stars we assess the detectability of planets as a function of R_p and P. We also correct for the geometric probability of transit, R*/a. We consider first stars within the "solar subset" having Teff = 4100-6100 K, logg = 4.0-4.9, and Kepler magnitude Kp < 15 mag. We include only those stars having noise low enough to permit detection of planets down to 2 Re. We count planets in small domains of R_p and P and divide by the included target stars to calculate planet occurrence in each domain. Occurrence of planets varies by more than three orders of magnitude and increases substantially down to the smallest radius (2 Re) and out to the longest orbital period (50 days, ~0.25 AU) in our study. For P < 50 days, the radius distribution is given by a power law, df/dlogR= k R^\alpha. This rapid increase in planet occurrence with decreasing planet size agrees with core-accretion, but disagrees with population synthesis models. We fit occurrence as a function of P to a power law model with an exponential cutoff below a critical period P_0. For smaller planets, P_0 has larger values, suggesting that the "parking distance" for migrating planets moves outward with decreasing planet size. We also measured planet occurrence over Teff = 3600-7100 K, spanning M0 to F2 dwarfs. The occurrence of 2-4 Re planets in the Kepler field increases with decreasing Teff, making these small planets seven times more abundant around cool stars than the hottest stars in our sample. [abridged]Comment: Submitted to ApJ, 22 pages, 10 figure

International Social Survey Programme: Work Orientations IV - ISSP 2015

Attitude towards work. Work orientation. Conflict and social exclusion. Subjective experience of job. Work satisfaction. Non-standard employment. Work life balance. Job and working flexibility. Human capital. Outcome of work. Employability, new job. Topics: work centrality (a job is just a way of earning money vs. would enjoy having a paid job even if the money is not needed); importance of selected demands of a job like job security, high income, etc. (work values); work life balance: willingness to give up good job opportunities for the benefit of the family; willingness to remain in a job that is not satisfying for the benefit of the family; conflict and social exclusion: experience of discrimination with regard to work, for instance when applying for a job; main reason for the discrimination; experience of harassment at the workplace by superiors or co-workers (for example bullying, physical or psychological abuse); solidarity and conflict with regard to trade unions (workers need strong trade unions to protect their interests vs. strong trade unions are bad for the country´s economy); preferred employment arrangements (full-time, part-time, less than 10 hours a week, no paid job at all); currently working for pay (employment status); preference for more work (and money) or for reduction in working hours (work longer hours and earn more money, work the same number of hours and earn the same money, or work fewer hours and earn less money); characteristics (social dimension) of own job; subjective experience of job: frequency of hard physical work and stressful work; non-standard employment: frequency of working at home during the usual working hours and working on weekends; job and working flexibility concerning starting and finishing times; non-standard employment: usual working schedule in the main job; job and working flexibility: organisation of daily work (free decision, decision within certain limits, no free decision); work life balance: difficult to take an hour off during working hours to take care of personal or family matters; demands of the job interfere with the family life and the demands of family life interfere with the job; human capital: usefulness of the abilities learned from past work experience for the present job; job training over the past twelve months to improve job skills; judgement on the relations between management and employees and the relations between workmates/ colleagues (working atmosphere); outcome of work: work satisfaction in the main job; identification with firm or organisation; occupational commitment (would change the present type of work for something different, proud of the present type of work); employability/ new job: expected difficulties in finding a new job at least as good as the current one; likeliness of job search in the next twelve months; worried about the possibility of losing own job; job and working flexibility: accepted concessions to avoid unemployment (acceptance of a job that requires new skills, acceptance of a lower paid position, acceptance of temporary employment, longer travel to reach the place of work, movement within the country, movement to a different country); existence of a side job in addition to the main job; earning from the additional job(s) in total compared with the main job. Respondents who are not currently employed were asked: ever worked for pay for one year or more; month and year the last paid job ended; work satisfaction in the last job; main reason for the end of last employment; interest in finding a paid job; expected difficulties in finding a new job; worried about the possibility of not finding a job; accepted concessions in order to get a job (acceptance of a job that requires new skills, acceptance of a lower paid position, acceptance of temporary employment, longer travel to reach the place of work, movement within the country, movement to a different country); job seeking activities in the past twelve months and training to improve own job skills; currently looking for a job; main source of economic support; worried about the possibility of losing this main economic support. Optional items: recent work histories: ever worked for pay over the past five years; experience of selected changes in working life (unemployment for a period longer than three months, change of the employer, change of the occupation, started own business/ became self-employed, took up an additional job); self-assessment of current financial situation; change of current financial situation compared to five years ago; expected financial situation in five years; attitude towards senior citizens´ work (good for the country´s economy, employed people aged 60 and over take jobs away from younger people). Optional background variable: self-assessment of physical and mental health. Additional compulsory background variable: age of the youngest child in the household. Demography: sex; age; year of birth; years in school; education (country specific); highest completed degree; work status; hours worked weekly; employment relationship; number of employees; supervision of employees; number of supervised employees; type of organisation: for-profit vs. non profit and public vs. private; occupation (ISCO-08); main employment status; living in steady partnership; union membership; religious affiliation or denomination (country specific); groups of religious denominations; attendance of religious services; top-bottom self-placement; vote in last general election; country specific party voted in last general election; party voted (left-right); self-assessed affiliation of ethnic group 1 and 2 (country specific); number of children; number of toddlers; size of household; earnings of respondent (country specific); family income (country specific); father´s and mother´s country of birth; marital status; place of living: urban – rural; region (country specific). Information about spouse/ partner on: work status; hours worked weekly; employment relationship; supervises other employees; occupation (ISCO-08); main employment status. Additionally encoded: respondent-ID number; date of interview (year, month, day); case substitution flag; mode of data collection; weight

International Social Survey Programme: Citizenship II - ISSP 2014

Citizen and state. Topics: Qualities of a good citizen; attitude towards the right of public meetings for religious extremists, people who want to overthrow the government by force, or people prejudiced against any racial or ethnic group; social and political participation; frequency of media use to get political news or information; number of people the respondent has contact with in a typical week day; active and passive memberships in different kinds of groups or associations (a political party, a trade union, business, or professional association, a church or other religious organization, a sports, leisure or cultural group); importance of different people´s rights in democracy (scale); suggestibility of the political system and personal level of information about politics; estimation of political influence possibilities (political efficacy): likeliness of counter-action against an unjust law and expected chance of serious attention to people´s demand; interest in politics; left-right self-placement; trust in politicians and people in government; estimation of people’s fairness; frequency of political discussions with friends; opinion leadership in politics; political parties encourage people to become active in politics; real policy choice between parties; attitude towards a referendum as a good way to decide important political questions; level of honesty and fairness in the last national election; commitment to serve people in public service; corruption in the public service; functioning of democracy in the country at present, in the past and in the future.Optional: frequencies of media use (read the political content of a newspaper, watch political news on television, listen to political news on the radio, use the Internet to get political news or information). Demography: Sex; age; year of birth; years in school; education (country specific); highest completed degree; work status; hours worked weekly; employment relationship; number of employees; supervision of employees; number of supervised employees; type of organization: for-profit vs. non profit and public vs. private; occupation (ISCO-08); main employment status; living in steady partnership; union membership; religious affiliation or denomination (country specific); groups of religious denominations; attendance of religious services; top-bottom self-placement; vote in last general election; country specific party voted in last general election; party voted (left-right); self-assessed affiliation of ethnic group 1 and 2 (country specific); number of children; number of toddlers; size of household; earnings of respondent (country specific); family income (country specific); father´s and mother´s country of birth; marital status; place of living: urban – rural; region (country specific). Information about spouse/partner on: Work status; hours worked weekly; employment relationship; supervises other employees; occupation (ISCO-08); main employment status. Additionally encoded: Date of interview; case substitution flag; weight; mode of data collection; group (participation in data collection mixed mode experiment)