Tri-band Minkowski Island Patch Antenna with Complementary Split Ring Resonator at the Ground Plane

Abstract—The Minkoski Island patch antenna with complementary split ring resonator at the ground plane are proposed in this work. At the first stage, the normal square patch antennas mainly designed. Then, the Minkowski patch antenna was designed using 1st iteration technique and 2nd iteration technique. The Minkowski fractal shape slot was embedded in the center of the patch to form a Minkowski Island patch antenna. The next step is to apply the partial ground technique and embed the split ring resonator at the ground plane. This antenna was operating in tri-band frequency that is at 2.400 GHz, 3.500 GHz and 5.200 GHz with a return loss of - 11.868 dB, - 13.554 dB and – 18.112 dB respectively. The gain measured of this antenna is 1.286 dB, 1.410 dB and 3.945 dB. Keywords—Minkowski Island, split ring resonator, patch antenna, return loss, gai

Reduced graphene oxide-multiwalled carbon nanotubes hybrid film with low Pt loading as counter electrode for improved photovoltaic performance of dye-sensitised solar cells

In this work, the role of reduced graphene oxide (rGO) with hyperbranched surfactant and its hybridisation with multiwalled carbon nanotubes (MWCNTs) and platinum (Pt) nanoparticles (NPs) as counter electrode (CE) were investigated to determine the photovoltaic performance of dye-sensitised solar cells (DSSCs). Sodium 1,4-is(neopentyloxy)-3-(neopentyloxycarbonyl)- 1,4-dioxobutane-2-sulphonate (TC14) surfactant was utilised as dispersing and stabilising agent in electrochemical exfoliation to synthesise graphene oxide (GO) as initial solution for rGO production prior to its further hybridisation and fabrication as thin film. A chemical reduction process utilising hydrazine hydrate was conducted to produce rGO due to the low temperature process and water-based GO solution. Subsequently, hybrid solution was prepared by mixing 1 wt% MWCNTs into the produced rGO solution. TC14-rGO and TC14-rGO_MWCNTs hybrid solution were transferred into fluorine-doped tin oxide substrate to fabricate thin film by spraying deposition method. Finally, the CE films were prepared by coating with thin Pt NPs. Photoanode film was prepared by a two-step process: hydrothermal growth method to synthesise titanium dioxide nanowires (TiO2 NWs) and subsequent squeegee method to apply TiO2 NPs. According to solar simulator measurement, the highest energy conversion efficiency (η) was achieved by using CE-based TC14-rGO_MWCNTs/Pt (1.553%), with the highest short current density of 4.424 mA/cm2. The highest η was due to the high conductivity of CE hybrid film and the morphology of fabricated TiO2 NWs/TiO2 NPs. Consequently, the dye adsorption was high, and the photovoltaic performance of DSSCs was increased. This result also showed that rGO and rGO_MWCNTs hybrid can be used as considerable potential candidate materials to replace Pt gradually

Design Minkowski Shaped Patch Antenna with Rectangular Parasitic Patch Elements for 5.8 GHz Applications

Abstract—This paper presents the parametric study on the Minkowski shaped antenna with the rectangular parasitic patch elements. This patch antenna consists four parts – patch, feed line, ground plane and parasitic elements. The rectangular parasitic patch elements are located at the bottom of the Minkowski shaped patch. The parametric study of different patch sizes (Design 2A, Design 2B, Design 2C, Design 2D and Design 2E) is presented in this paper. The antenna parameters studied in this paper are resonant frequencies, return loss at the resonant frequency, bandwidth and realized gain. The target frequency of this antenna is 5.80 GHz for Worldwide Interoperability for Microwave Access (WiMAX) application. It shows the return loss of – 24.477 dB, bandwidth of 254 MHz (5.676 GHz to 5.930 GHz) and a gain of 2.351 dB. Index Terms—Minkowski; patch antenna; gain; return loss; bandwidt

Length-weight relationships for 13 fish species from the Gulf of Gabes (Southern Tunisia, Central Mediterranean)

Length-weight relationships (LWR) were estimated for 13 fish species which are of economic relevance in the commercial fisheries of the Gulf of Gabes (southern Tunisia). A total of 2403 fish specimens were sampled with several fishing gears from October 2008 to September 2009. The sample size ranged from 65 individuals for Coryphaena hippurus to 346 for Euthynnus alletteratus. The b values in the LWR, W = aLb ranged from 2.807 to 3.284, with a mean of 3.015 ± 0.102 and intercepts between 0.0011 and 0.0432 with a mean of 0.0139. The condition factor (c.f.) values significantly (p < 0.05) ranged from 0.64 to 1.55.Key words: Gulf of Gabes, length-weight, fish species, condition factor

Effect of Single Complimentary Split Ring Resonator Structure on Microstrip Patch Antenna Design

This paper had been comparing the performance of the normal patch antenna with single complimentary SRR patch antenna. Four different shapes of single complimentary split ring resonator structure had been incorporated into the microstrip patch antenna - square, circular, triangular, and rhombic. This simulation works had been done in CST Microwave Studio simulation software. The operating frequency of this antenna is 2.40 GHz for Wireless Local Area Network (WLAN) application.The parameters that considered in these works are return loss,resonant frequency, input impedance, gain, radiation pattern and bandwidth. The focusing parameter is to achieve the best gain performance that obtained from the single complimentary split ring resonator patch antenna. The addition of square SRR onto patch antenna will improve the gain from 6.334 dB to 6.508 dB

The Challenges of Psychological Adjustment for International Students: A Critical Analysis of Coping Mechanisms and Support Services

This paper critically analyzes the challenges of psychological adjustment faced by international students and explores coping mechanisms and support services that can help them overcome these challenges. The essay first introduces the background information on international students and highlights the importance of psychological adjustment for their well-being and academic success. The challenges of psychological adjustment, including cultural, academic, social adjustment, and language barrier, are discussed in detail. The essay then explores coping mechanisms, including problem-focused coping, emotion-focused coping, seeking social support, and cultural adjustment programs, and the support services, including counseling services and international student services, that can help international students adjust to their new environment. Finally, the essay evaluates the effectiveness of these coping mechanisms and support services, emphasizing the importance of cultural competence in providing effective support services. This essay has practical implications for higher education institutions in providing tailored support to international students and highlights the need for future research to explore the effectiveness of coping mechanisms and support services for different groups of international students and the impact of the COVID-19 pandemic on their psychological adjustment

The Effect of Social Isolation on the Mental Health of International Students

This paper looks into how social isolation affects international college students mental health. An increase in international students studying at colleges and universities abroad can be attributed to increased global mobility over the previous few decades. Because of this, these students struggle in certain ways to fit into their new academic and social surroundings. Among these difficulties, social isolation among overseas students has been recognized as a major issue. This essay will investigate how social isolation affects the mental health of international college students by drawing on existing studies. The various types of social isolation will be covered in the essay along with how they may affect mental health. It will also be looked at whether factors like linguistic difficulties, cultural shock, prejudice, and discrimination contribute to social isolation among overseas students. In light of the hazards to mental health posed by social isolation among international students, this presentation will offer some potential solutions. The findings of the inquiry will be utilized to create solutions that can assist overseas students in reducing the detrimental impacts of social isolation on their mental health. Compared to other groups, college students’ mental health has not been adequately researched, even though social isolation can be an emotionally and mentally damaging experience. The paper will focus on the various mental health impacts that international college students experience such as depression, anxiety, and long-term psychological harm. An analysis of existing literature on the topic, interviews with international college students, and the mental health resources available to this population are also discussed. The main findings of the research show that international college students living in a foreign country experience significant levels of social isolation due to language barriers and cultural differences

Effect of Spiral Split Ring Resonator (S-SRR)structure on Truncated Pyramidal Microwave Absorber Design

This paper discusses on the effect of the spiral split ring resonator on the truncated pyramidal microwave absorber. Split ring resonator (SRR) structure can potentially be incorporated onto the truncated pyramidal microwave absorber to increase the reflection loss performance. There are many ways to increase the pyramidal microwave absorber performance. The ways are focusing the new hybrid shapes, using high carbon material, and adding the left handed material structure on the pyramid microwave absorber. Left handed material or metamaterial is an artificial material that does not exist in the real nature like FR4, Taconic, Rogers or RT Duriod.There are many types of left handed material that had been used by several researchers such as split ring resonator (SRR), and photonic band gap (PBG), electromagnetic band gap (EBG) and artificial magnetic conductor (AMC). In this research, spiral split ring resonator (S-SRR) is used to increase the microwave absorber performance. It has the potential to increase the reflection loss or 811 results of the microwave absorber at the several frequencies

STUDY AND SIMULATION OF AN EDGE COUPLE SPLIT RING RESONATOR (EC-SRR) ON TRUNCATED PYRAMIDAL MICROWAVE ABSORBER

Split ring resonator (SRR) structure can potentially be incorporated onto the truncated pyramidal microwave absorber. This study considers three different patterns of edge couple split ring resonator (EC-SRR) designs. Each EC-SRR design is then placed onto the truncated pyramidal microwave absorber. Outer split gap dimension widths of the EC-SRR are varied, and the various S21 performances are compared. This EC-SRR truncated pyramidal microwave absorber is simulated using CST Microwave Studio simulation software. The study and simulation are performed in low frequency range (0.01 GHz to 1 GHz) as well as in microwave frequencies range (1 GHz to 20 GHz). Simulation results of this EC-SRR show improvement of reflection loss and S11 performance in the high frequency range of the pyramidal truncated microwave absorber

Particle swarm algorithm sliding mode control on spacecraft’s attitude with switching function method thorough error feedback

Small spacecraft requires capable processors with energy efficiency, low cost and low computational burden while maintaining the output tracking accuracy. This paper presents the extension of work in [1], to enhance the transient performance using particle swarm optimization (PSO) on decaying boundary layer and switching function thorough error feedback (DBLSF) in Sliding Mode Control (SMC). Generally, SMC is known for having chattering as the main drawback which can introduce wear and tear to moving mechanical parts. As a solution, a DBLSF proposed in [1] and capable of eliminating the chattering in SMC while considering the essential requirements for small spacecraft operation. Then, the extension implemented on spacecraft's attitude, which is one-of-six subsystems in spacecraft, used to orient the spacecraft referred to reference objects and control the dynamics of a spacecraft time-to-time according to the needs. However, the SMC's transient response can be tuned using some coefficients in the SMC algorithm. The parameters in [1] were tuned using outputs observation technique. In this paper, then, an improvement is introduced to optimize the outputs by adding a PSO in the SMC-DBLSF in term of transient performances and accuracy while reducing the chattering permanently