Axially symmetrical Fabry-Perot oscillator with multiple devices inserted in dielectric substrate

We investigate an axially symmetrical Fabry-Perot oscillator with active devices inserted in a dielectric substrate for power combining of many more devices in the microwave and millimeter wave frequency range. Empirically in this oscillator, efficient power combining can be done when it oscillates approximately at the frequency which corresponds to the wavelength equal to twice the spacing between the devices. The wavelength in the dielectric is shorter than in free space, so we tried to insert the devices in the dielectric substrate in order to increase the number of devices. By measuring the oscillation frequency of the oscillator with sixteen devices at X-band, we confirmed that the spacing between devices was about a half wavelength in the dielectric. We achieved almost perfect power combining of sixteen device

Teachers' Misunderstanding The Concept Of Inclusive Education

Teachers' misunderstanding the concept of inclusive education will not lead to good practices, rather make an exclusive environment for pupils with special educational needs in mainstream schools. This study clarified teachers' attitudes towards the image of inclusive education with conjoint analysis and cluster analysis. The participants for this study were 182 teachers who were from both mainstream schools and special schools. Their image about inclusive education was mainly dependent upon the organization of group and size of a group. The subfile summary of the conjoint analysis indicated that the teacher's views of inclusive education as images of "expanding school environment to include a child", withdrawal to "resource room", "small groups", and "a pupil with disability in a mainstream group." On the other hand, images of "repudiation of segregated learning opportunities", "homogeneous group", "a large size group", and "various attributes in a group" were perceived as "non-inclusive." The author has divided the participants into two groups by cluster analysis. The factors in dividing were discussed as not depend on their teaching experience nor school type, but local school environment - such as enrollment ratio of foreign pupils

Complex formation and enantioselectivity studies of triazole fungicide and organophosphorus pesticide enantiomers using capillary electrophoresis

Several cyclodextrin modified-micellar electrokinetic chromatography (CDMEKC) methods were developed for the successful triazole fungicides separation. In the first part, an efficient method was developed for the simultaneous enantioseparation of cyproconazole (4 stereoisomer), bromuconazole (4 stereoisomer) and diniconazole (2 stereisomer) enantiomers using CD-MEKC with a dual mixture of neutral cyclodextrins as chiral selector. The best simultaneous separation of cyproconazole, bromuconazole, and diniconazole enantiomers was achieved with a mixture of 27 mM HP-β-CD and 3 mM HP-γ-CD in 25 mM phosphate buffer (pH 3.0) containing 40 mM sodium dodecyl sulfate (SDS) and 15% iso-propanol as organic modifier. Complete separation of 10 stereoisomer of triazole fungicides were obtained in a single run with good resolution (Rs 1.74“26.31) and high peak efficiency (N > 400 000). In the second part of the study, enantioseparation of hexaconazole, penconazole, myclobutanil, and triadimefon was investigated. Simultaneous enantioseparation of penconazole, myclobutanil, and triadimefon was achieved under acidic condition (pH 3.0) using 25 mM phosphate buffer, 50 mM SDS, and 30 mM HP-γ-CD, with Rs greater than 0.9 whereas, simultaneous enantioseparation of hexaconazole, penconazole, and myclobutanil was successfully achieved under neutral condition (pH 7.0) using 25 mM phosphate buffer, 40 mM SDS, and 40 mM HP-γ-CD, with Rs greater than1.6. In order to improve detection sensitivity, on-line preconcentration technique was investigated. It was found that sweeping technique as an on-line preconcentration technique improved the detection sensitivity of the enantioseparation of cyproconazole, bromuconazole, and diniconazole by 30 to 60-fold, with good repeatabilities in the migration time, peak area and peak height were obtained with RSDs in the range of 0.08“0.32%, 0.03“ 2.44%, and 2.13“8.44% respectively. Furthermore, sweeping technique improved the detection sensitivity of the enantioseparation of hexaconazole, penconazole and myclobutanil by 62- to 67-fold. Good repeatabilities in the migration time, peak area and peak height were obtained with RSDs in the range of 2.39“3.90%, 1.96€“6.15%, and 2.80“6.64% respectively. Finally, the formation constant of diniconazole enantiomers with HP-γ-CD under neutral and acidic condition was investigated using CD-MEKC

Selectivity and applications of supercritical fluid chromatography

Supercritical fluid chromatography (SFC) has been undergoing tremendous developments in recent years as an attractive technique that is complementary to both gas and liquid chromatography. The main aim of this study has been to examine selectivity in SFC by using retention indices as the means of recording retention and to explore the potential applications of this novel technique. A simple supercritical fluid chromatograph was constructed based on a Pye-Unicam gas chromatograph and a HPLC pump. SFC separations were carried out using HPIC packed columns with pure or modified carbon dioxide as the mobile phase and using ultraviolet and flame ionization detection. The effects of different parameters on the retention of compounds. of different functional groups have been studied. At a given temperature, the capacity factors of the compounds generally decreased with increases in pressure (density). Little change in selectivity was observed between compounds in a homologous series but selectivity differences were observed between compounds of different functionalities and anomalous behaviour was seen for acetophenone on a cyano-silica column. Temperature can also be used to selectively modify the retention of the analytes. The use of methanol or acetonitrile as the organic modifier generally improved the peak shapes and reduced the retentions, and this was particularly marked for polar compounds. Similar trends in retentions were observed for PS-DVB, ODS-, and cyano-silica columns although the compounds were generally more retained on the PS-DVB column, suggesting that the selectivity was controlled mainly by the properties and compositions of the mobile phase. Using different sets of homologues, alkylarylketones, n-alkanes, and alkylbenzenes, the possibility of the application of retention indices in SFC was investigated. The use of retention indices have been shown to have advantages over capacity factors, but unlike HPLC, retention indices in SFC are much more susceptible to selectivity changes caused by variations in the operating parameters. Studies were carried out to demonstrate the viability of SFC for the separation of several drug groups, barbiturates and benzodiazepines. With no modifier in the mobile phase, these compounds were highly retained on the columns, particularly on ODS- and cyano-silica. Successful separations of the drug compounds were achieved with methanol or acetonitrile as the modifier in the mobile phase. The application of the SFC system was extended to the separations of several terpenes and the leaf essential oil of Cymbopogon martinii (Roxb.) Wats on a PS-DVB column. The results were compared with those obtained using GC and GC-MS methods and it was evident that the GC methods gave better resolutions and sensitivity and would still be the method of choice

Hyper NRD guide oscillator with Gunn diodes mounted in the dielectric strip

Hyper NRD guide oscillators mounted with a single and multiple Gunn diodes have been investigated. The operating mode of the hyper NRD guide can be lower order by optimizing the structure of the guide. The Gunn diodes were arranged in the dielectric strip of the guide. In experiments at X-band, the oscillation frequencies could be varied by a movable shorting plane for the single diode case and an almost perfect power combining was obtained for the double diode cas

Axially symmetric Fabry-Perot power combiner with active devices mounted on both the mirrors

We investigate an axially symmetrical Fabry-Perot power combiner with many more active devices operating in axially symmetric TEM01n mode, which has an excellent feature of uniform device-field coupling required for high power combining efficiency. By numerical calculation using the boundary element method, it was shown that high combining efficiency can be obtained when a circular groove of larger radius is installed on either the plane mirror or the concave mirror. In experiments at X-band, almost perfect power combining of twenty or twenty-four Gunn diode oscillators mounted on both of the mirrors was achieve

Single and multiple Gunn diode oscillator using an image NRD guide

A single and a multiple Gunn diode oscillator using an image NRD guide have been investigated. The LSM01 mode which is the operating mode of the image NRD guide can be the dominant mode because undesired modes are suppressed due to existence of the image plane. In experiments at X-band for oscillators with Gunn diodes mounted in the dielectric strip of the image NRD guide, the oscillation frequencies could be varied by a movable shorting plane for the single diode case and an effective power combining operation was obtained for the double diode cas

Traveling-wave power divider with coplanar waveguide probes inserted into rectangular waveguide

A new traveling-wave power divider with coplanar waveguide probes is investigated. The divider is constructed by connecting successively the dividing units which consist of coplanar waveguide probe-pairs inserted into a rectangular waveguide and the thin narrow section. From experiments on fourand six-way dividers, wideband characteristics comparable to a divider with coaxial probes is demonstrate

Traveling-wave microwave power divider composed of reflectionless dividing units

We propose a new waveguide type traveling-wave microwave power divider that is adequate for high power applications. The divider is composed of multiple stages of reflectionless dividing units, each having two output ports. Design formulas for reflectionless equal-power dividing are first derived. Structural parameters for wideband design of two- to six-stage dividers are then obtained by means of numerical analyses based on an equivalent circuit. Comparison of experiments at X-band shows good qualitative agreement with the analyses. Typical measured bandwidth for relative divided powers deviation of less than ±0.5 dB was 2.7 GHz, and that for -20 dB return loss was more than 3.2 GHz for the four-stage (eight-way) divider. The divider presented here has excellent features; the bandwidth for equal-power dividing decreases very little and the bandwidth for low return loss increases with increasing number of the dividing stages. It also has advantages of low insertion loss and flexibility over the number of the dividing stage