Quadrature Phase Shift Keying (QPSK) Modulator Design using Multi-Port Network in Multilayer Microstrip-Slot Technology for Wireless Communication Applications

The design of the quadrature phase shift keying (QPSK) modulator by using a multi-port network is proposed in this article for the use in wireless communication applications. The multi-port network is in the form of multilayer microstrip-slot technology. This multi-port network is composed of three 3-dB rectangular-shaped directional couplers with virtual stubs and an equal power division divider with in-phase characteristic. The design is performed by applying a full-wave electromagnetic simulation software, CST Microwave Studio (CST MWS). Keysight’s Advanced Design System (ADS) is applied in analyzing and evaluating the QPSK constellation of the proposed modulator. This comparatively small size of proposed design has been fabricated, and its wideband performance of 2 to 6 GHz is verified

Bistable behavior of a two-mode Bose-Einstein condensate in an optical cavity

We consider a two-component Bose-Einstein condensate in a one-dimensional optical cavity. Specifically, the condensate atoms are taken to be in two degenerate modes due to their internal hyperfine spin degrees of freedom and they are coupled to the cavity field and an external transverse laser field in a Raman scheme. A parallel laser is also exciting the cavity mode. When the pump laser is far detuned from its resonance atomic transition frequency, an effective nonlinear optical model of the cavity-condensate system is developed under Discrete Mode Approximation (DMA), while matter-field coupling has been considered beyond the Rotating Wave Approximation. By analytical and numerical solutions of the nonlinear dynamical equations, we examine the mean cavity field and population difference (magnetization) of the condensate modes. The stationary solutions of both the mean cavity field and normalized magnetization demonstrate bistable behavior under certain conditions for the laser pump intensity and matter-field coupling strength.Comment: Proceeding of Laser Physics 201

Kita tutup aurat! : aplikasi pembelajaran menutup aurat untuk kanak-kanak

Menutup aurat adalah salah satu kewajipan dalam agama Islam. Oleh itu, pemahaman konsep menutup aurat adalah asas yang perlu dipelajari pada usia muda. Namun begitu, kanak-kanak hanya belajar menutup aurat mengikut konsep teori pembelajaran sahaja di sekolah. Kanak-kanak sukar mengikuti dan memahami pembelajaran yang menggunakan konsep teks dan fakta. Justeru itu, aplikasi pembelajaran yang berkonsepkan pembelajaran mudah alih (m-pembelajaran) yang dinamakan “Kita Tutup Aurat!” mengenai aurat untuk kanak-kanak ini dibangunkan. Aplikasi ini dibangunkan dengan menggunakan model ADDIE kerana kesesuaiannya dalam pembangunan aplikasi pembelajaran. Pengujian aplikasi telah dijalankan oleh 30 responden dari kalangan kanak-kanak sekolah rendah sekitar Parit Raja serta beberapa orang guru. Hasil pengujian menunjukkan lebih 70% responden bersetuju aplikasi yang dibangunkan merupakan satu pendekatan menarik dalam mempelajari dan memahami konsep menutup aurat dalam Islam. Kesimpulannya, aplikasi telah berjaya mencapai objektif yang telah ditentukan kerana ia menepati kehendak pengguna dan mempunyai fungsi-fungsi yang terkandung dalam skop sistem. Secara keseluruhan, implementasi aplikasi pembelajaran ini berpotensi untuk dijadikan kaedah alternatif dalam memahami konsep aurat sekaligus mendidik kanak-kanak untuk menutup aurat dengan sempurna

Emergence of turbulence in an oscillating Bose-Einstein condensate

We report on the experimental observation of vortices tangle in an atomic BEC of Rb-87 atoms when an external oscillatory perturbation is introduced in the trap. The vortices tangle configuration is a signature of the presence of a turbulent regime in the cloud. We also show that this turbulent cloud has suppression of the aspect ratio inversion typically observed in quantum degenerate bosonic gases during free expansion. Instead, the cloud expands keeping the ratio between their axis constant. Turbulence in atomic superfluids may constitute an alternative system to investigate decay mechanisms as well as to test fundamental theoretical aspects in this field.Comment: accepted for Phys. Rev. Let

Connecting dissipation and phase slips in a Josephson junction between fermionic superfluids

We study the emergence of dissipation in an atomic Josephson junction between weakly-coupled superfluid Fermi gases. We find that vortex-induced phase slippage is the dominant microscopic source of dissipation across the BEC-BCS crossover. We explore different dynamical regimes by tuning the bias chemical potential between the two superfluid reservoirs. For small excitations, we observe dissipation and phase coherence to coexist, with a resistive current followed by well-defined Josephson oscillations. We link the junction transport properties to the phase-slippage mechanism, finding that vortex nucleation is primarily responsible for the observed trends of conductance and critical current. For large excitations, we observe the irreversible loss of coherence between the two superfluids, and transport cannot be described only within an uncorrelated phase-slip picture. Our findings open new directions for investigating the interplay between dissipative and superfluid transport in strongly correlated Fermi systems, and general concepts in out-of-equlibrium quantum systems.Comment: 6 pages, 4 figures + Supplemental Materia

Efficient all-optical production of large 6^6Li quantum gases using D1_1 gray-molasses cooling

We use a gray molasses operating on the D$_1$ atomic transition to produce degenerate quantum gases of $^{6}$Li with a large number of atoms. This sub-Doppler cooling phase allows us to lower the initial temperature of 10$^9$ atoms from 500 to 40 $\mu$K in 2 ms. We observe that D$_1$ cooling remains effective into a high-intensity infrared dipole trap where two-state mixtures are evaporated to reach the degenerate regime. We produce molecular Bose-Einstein condensates of up to 5$\times$10$^{5}$ molecules and weakly-interacting degenerate Fermi gases of $7\times$10$^{5}$ atoms at $T/T_{F}<0.1$ with a typical experimental duty cycle of 11 seconds.Comment: 5 pages, 3 figure

Towards a predictive model for incoming thermal fluxes during a fuel warehouse fire

The prediction of released heat fluxes from fires is mandatory for any fire safety strategy. Indeed, the spreading time and directions of thermal fluxes are particularly critical in the situations of fuel warehouses, where temperature levels can induce primary and secondary inflammations in the neighbouring depots. Moreover, firefighters should operate in areas where the thermal environment is tolerable and in favour of efficient egress operations. Several correlative models provided by some industrial organizations are applied to the study case of Naftal-Chiffa fuel warehouse (Blida, Algeria). Various fire characteristics are predicted, in particular height and inclination of jet flames, in addition to the spatial distribution of heat fluxes on solid targets (human bodies and structures). The analyses reveal that the safety distances corresponding to the threshold fluxes of 3 kw/m2, 5 kw/m2 and 8 kw/m2 as provided by the IT-89 correlations, exhibit an important dispersion when relative humidity was different from 70% and the fuel tank was had no longer a square shape. In this direction, the present study was completed with a parametric analysis on the effects of climatic conditions (ambient temperature, relative humidity, wind speed) and storage tanks geometry on the distances relates to critical thermal fluxes.info:eu-repo/semantics/publishedVersio