Open-ended microwave oven for flip-chip assembly

A novel open-ended waveguide cavity resonator for the microwave curing of bumps, underfills and encapsulants is described. The open oven has the potential to provide fast alignment of devices during flip-chip assembly, direct chip attach, surface mount assembly or wafer-scale level packaging. The prototype microwave oven was designed to operate at X-band for ease of testing, although a higher frequency version is planned. The device described in the paper takes the form of a waveguide cavity resonator. It is approximately square in cross-section and is filled with a low-loss dielectric with a relative permittivity of 6. It is excited by end-fed probes in order to couple power preferentially into the TM3,3,k mode with the object of forming nine 'hot-spots' in the open end. Low power tests using heat sensitive film demonstrate clearly that selective heating in multiple locations in the open end of the oven is achievable.

Increased Bandwidth Evanescent Open-Ended Waveguide Antenna Design Using the Imaginary Smith Chart

We present a novel antenna matching technique that uses the Imaginary Smith Chart to permit wideband matching of an evanescent open-ended waveguide antenna using a dielectric sheet air-spaced from the aperture. The fabricated antenna design is demonstrated to have a measured bandwidth of 24%, from 2.13–2.7 GHz, for reflection coefficient $qquad{<} -!!10~{rm dB}$ , with 2.725 GHz waveguide cutoff. The antenna's maximum aperture dimension is ${< 0.5}lambda_{0}$ at the upper frequency in the bandwidth and so it is suitable for use in a wide angle scanning phased array

The inclusion of open-ended questions on quantitative surveys of children: Dealing with unanticipated responses relating to child abuse and neglect

Web surveys have been shown to be a viable, and relatively inexpensive, method of data collection with children. For this reason, the Kids’ Life and Times (KLT) was developed as an annual online survey of 10 and 11 year old children. Each year, approximately 4,000 children participate in the survey. Throughout the six years that KLT has been running, a range of questions has been asked that are both policy-relevant and important to the lives of children. Given the method employed by the survey, no extremely sensitive questions that might cause the children distress are included. The majority of questions on KLT are closed yielding quantitative data that are analysed statistically; however, one regular open-ended question is included at the end of KLT each year so that the children can suggest questions that they think should be asked on the survey the following year. While most of the responses are innocuous, each year a small minority of children suggest questions on child abuse and neglect. This paper reports the responses to this question and reflects on how researchers can, and should, deal with this issue from both a methodological and an ethical perspective.

Brilliant activities for stretching gifted and talented children : open-ended mental stimulation activities.

Manual que ayuda a padres y profesores a prestar a los niños superdotados y con talento la estimulación mental que necesitan. En la primera parte se hacen comentarios, teorías, por ejemplo, la taxonomía de Bloom, y conceptos relacionados con la creatividad, el aprendizaje y la enseñanza. La segunda parte ofrece una selección de actividades para toda la clase: rompecabezas y ejercicios entretenidos de matemáticas. La tercera parte proporciona entretenimientos de composición abierta, ejercicios independientes para los alumnos. Todas las actividades son fotocopiables. Aunque escrito principalmente para alumnos excepcionales hasta la edad de once años, este recurso presenta enfoques e ideas que pueden aplicarse a cualquier alumno y a cualquier situación de enseñanza.

German open ended funds: was there a valuation problem?

In late 2005, a number of German open ended funds suffered significant withdrawals by unit holders. The crisis was precipitated by a long term bear market in German property investment and the fact that these funds offered short term liquidity to unit holders but had low levels of liquidity in the fund. A more controversial suggestion was that the crisis was exacerbated by a perception that the valuations of the fund were too infrequent and inaccurate. As units are priced by reference to these valuations with no secondary market, the valuation process is central to the process. There is no direct evidence that these funds were over-valued but there is circumstantial evidence and this paper examines the indirect evidence of the process to see whether the hypothesis that valuation is an issue for the German funds holds any credibility. It also discusses whether there is a wider issue for other funds of this nature or whether it is a parochial problem confined to Germany. The conclusions are that there is reason to believe that German valuation processes make over-valuation in a recession more likely than in other countries and that more direct research into the German valuation system is required to identify the issues which need to be addressed to make the valuation system more trusted.

Investigative interviewers' perceptions of their difficulty in adhering to open-ended questions with child witnesses

Best practice guidelines for conducting investigative interviews of children emphasise the importance of obtaining free narrative accounts with the use of open-ended questions. However, research indicates that most investigative interviewers underutilise open-ended questions, even following intensive training in their use. The aim of the current study was to explore investigative interviewers' perceptions of their difficulty in asking open-ended questions. During a training course on how to use open-ended questions, eight child abuse investigators were individually interviewed about why they had asked specific questions in a 10-minute mock interview conducted immediately earlier with a school child. Overall, three reasons were identified. These related to: 1. the specificity of the information required from children; 2. the unfamiliar nature of the open-ended discourse style; and 3. the complex distinction between open-ended versus specific questions. Each of these themes is discussed, along with the implications for trainers and researchers in child investigative interviewing.

The importance of using open-ended questions when interviewing children

In addition to making reference to best practices, already known, concerning the conduct of interviews with child victims of sexual abuse, the author describes some of the questions of development that must be made and the four benefits of free narrative. Despite the qualities of this type of approach, surveys show that professionals do not get the research, as a rule, free of narrative descriptions by children and that interviews tend to contain the short answer questions, with few breaks and an excessive number of closed questions and trick.According to trainers, experts in this field, there should be greater recognition of the interview as a forensic specialist skills and promote themselves to more effective supervision and monitoring of the forensic interview at work.

Open ended tasks and barriers to learning : teachers' perspectives

Examines barriers to learning mathematics when using an open-ended task teaching strategy. Features of an open-ended task; Benefits of an open-ended task; Problems concerning multiplicity of responses and contexts in an open-ended task.

Opening up open-ended mathematics tasks

This discussion has evolved from ideas in Peter Sullivan and Pat Lilburn's Open-Ended Maths Activities; Using 'Good' Questions to Enhance Learning (1997). This is a compilation of open-ended questions, and methods for generating open-ended questions, along with a brief rationale for using such questions. This classroom-oriented teaching resource developed from earlier research and teaching development work by Peter Sullivan and David Clarke, and others. Two methods are offered for constructing a 'good question'.