Tensile Properties of Z-Pin Reinforced Laminates with Circumferentially Notched Z-Pins

This paper describes experimental investigations on the in-plane tensile properties of unidirectional carbon-fibre/epoxy laminates reinforced with circumferentially notched z-pins with different notch designs. From the results it can be concluded that the application of circumferential notches at the z-pin surface with constant notch depth of 20 μm and distance of 100 μm has no significant effect on the in-plane tensile strength values, regardless of the notch designs investigated. For circular and rectangular notch designs, no dependence of the tensile strength from the notch depth could be observed. Only changing the notch distances at a constant notch depth and width leads to small increases in the tensile strength values with increasing notch distance. The determined tensile modulus values indicate that there are no substantial deviations between laminates reinforced with unnotched and circumferentially notched z-pins, no matter which notch design is considered. It can be observed that there are no dependencies of the tensile modulus from notch depth and distance. Therefore, it can be assumed that the microstructural changes influencing the in-plane tensile properties will not be changed, or only to a very small extent, by the presence of notches on the pin surface.

Feather-shaped super wideband MIMO antenna

Two configurations of a modified feather-shaped antenna element are proposed for super wideband (SWB) multiple-input multiple-output (MIMO) applications. The antenna element geometry comprises of a circular slot-loaded feather-shaped radiator and rectangular notch-loaded quarter elliptical coplanar waveguide ground plane. An operating bandwidth of 4.4–51.5 GHz with inter-port isolation, S21 ≥ 15 dB for spatial diversity configuration, and 3.8–51.5 GHz with S21 ≥ 15 dB in pattern diversity configuration are achieved. The footprints of the antenna configurations are 17 × 33 and 31 × 31 mm2. Both configurations exhibited an envelope correlation coefficient of <−20 dB. The proposed MIMO configurations are fabricated and experimentally validated. The designed antenna configurations are SWB and compact.

A Rectangular Notch-Band UWB Antenna with Controllable Notched Bandwidth and Centre Frequency

This paper presents the design and realization of a compact ultra-wideband (UWB) antenna with a rectangular notch wireless area network (WLAN) band that has controllable notched bandwidth and center frequency. The UWB characteristics of the antenna are achieved by truncating the lower ends of the rectangular microstrip patch, and the notch characteristics are obtained by using electromagnetic bandgap (EBG) structures. EBGs consist of two rectangular metallic conductors loaded on the back of the radiator, which is connected to the patch by shorting pins. A rectangular notch at the WLAN band with high selectivity is realized by tuning the individual resonant frequencies of the EBGs and merging them. Furthermore, the results show that the bandwidth and frequency of the rectangular notch band could be controlled according to the on-demand rejection band applications. In the demonstration, the rectangular notch band was shifted to X-band satellite communication by tuning the EBG parameters. The simulated and measured results show that the proposed antenna has an operational bandwidth from 3.1–12.5 GHz for |S11| < -10 with a rectangular notch band from 5–6 GHz, thus rejecting WLAN band signals. The antenna also has additional advantages: the overall size of the compact antenna is 16 × 25 × 1.52 mm3 and it has stable gain and radiation patterns.

Dual Band-Notched Rectangular Dielectric Resonator Antenna with Tunable Characteristic

A dual band-notched reconfigurable dielectric resonator antenna (DRA) is proposed in this paper. A rectangular dielectric resonator excited by stepped offset microstrip feedline generates multiple resonant modes for wideband performance. Moreover, the typical stepped impedance feedline and partial ground plane with one rectangular notch are adopted for contributing for better impedance matching. On this basis, a five-line coupler resonator (FLCR) composed by inverted U-shaped and 山-shaped structures is introduced as a bandstop filter in the microstrip feedline, and dual rejected bands are created. Tunable notched frequencies are achieved by the varactor between these two structures. The proposed antenna size is 24 × 28 × 5.637 mm3. For the presented work, both simulated and measured results for the proposed tunable antenna ranging from 5.3 to 5.84 GHz and from 8.74 to 8.98 GHz within the wide bandwidth of 6.06 GHz are presented, demonstrating the accuracy of this design. There capabilities make the proposed antenna applicable for wideband systems with the requirement of avoiding interferences.

ANALISIS DEBIT AIR DENGAN VARIASI BENTUK OPEN CHANNEL DENGAN PENAMPANG SEGITIGA, PERSEGI, DAN TRAPESIUM PADA SUATU ALIRAN

An open channel is a channel where water flows with free water. In open channels, such as rivers (natural channels), channel parameters are very irregular. Damming the channel is a transition that serves to determine the height of the water surface along the channel, on this issue the author examines how water flows when through open channel with v-notch, rectangular and trapezoidal shapes in a stream. Based on the test results on 35° valve angle variations, the increase debit from the v-notch debit leads to a rectangular-notch debit of 23.63% and the largest decrease in debit from the rectangular notch to trapezodial-notch is 48.38%. In the valve angle variation 40°, the largest increase in debit between the v-notch discharge towards a rectangular-notch discharge of 18.64% and the decrease in the largest debit from rectangular-notch to trapezodial-notch at 45.31%. In the valve angle variation 45° the largest increase debit between the v-notch debit towards a rectangular-notch debit is 18.64% and the largest decrease debit from the rectangular notch to trapezodial-notch debit is 46.15%.