The moderating effect of change agent and organizational climate on the total quality management and organisational sustainability in Saudi Arabia hotel industry

Saudi hotel industry still has not performed to their fullest potential. The industry has to focus on quality improvement efforts to improve their performance. Therefore, this study is undertaken to examine the impact of total quality management (TQM) practices on the sustainability of the Saudi hotel industry. It also aims to investigate the moderating effect of change agent and organisational climate on the total quality management (TQM) practices-sustainability relationship of the Saudi hotel industry. This study was motivated by the inconsistency of findings reported in the literature regarding the relationship of total quality management practices, change agent and organisational climate variables, with sustainability. Such inconsistencies have led to the emergence of a new research stream that recommended the investigation of the moderating variables that could contribute to the aforementioned relations between variables. In the present study, different theories were employed including the social exchange theory and the resource-based view theory, to provide an insight into the relationships among variables in the proposed conceptual framework. The study involved survey questionnaire which were randomly distributed to 932 hotels in five cities of Saudi. Out of the total number of retrieved questionnaires (238), 204 were usable for analysis. The researcher employed correlation and hierarchical regression analysis to analyze the study variables indirect and direct relationships. The results show a positive relationship between the TQM and the organisational sustainability, and they support the moderating effects of both change agent and organisational climate on the TQM-organisational sustainability relationship. The study is concluded by providing managerial, policy and theoretical implications as well as recommendations for future studies

Broadband Bow-Tie Slot Antenna with Tuning Stub for Resonant Tunnelling Diode Oscillators with Novel Configuration for Substrate Effects Suppression

Radiation from antennas integrated with InP-based resonant tunnelling diode (RTD) oscillators is usually degraded because of the effects of the large dielectric constant substrate. The common solution has been to use hemispherical lenses to extract the signal from the backside of the substrate. In this paper we present a broadband bow-tie slot antenna with tuning stub which is diced and mounted on a ground plane to alleviate the substrate effects. Here, the large dielectric constant substrate around the antenna conductor is removed. In addition, the ground plane underneath the diced substrate acts as a reflector and, ultimately, the antenna radiates to air-side direction. The antenna was designed and fabricated using photolithography techniques to offer wide bandwidth (return loss S11 <-10dB) between 200-350 GHz on semi-insulating InP substrate with dielectric constant of ϵr = 12.56. Simulated and measured bandwidth almost extends the frequency range 230-325 GHz. Simulations shows air-side radiation pattern, an antenna gain of around 11 dB at 290 GHz and 98% radiation efficiency

Diced and grounded broadband bow-tie antenna with tuning stub for resonant tunnelling diode terahertz oscillators

Radiation from antennas integrated with indium phosphide (InP)-based resonant tunnelling diode (RTD) oscillators is mainly through the substrate because of the effects of the large dielectric constant. Therefore, hemispherical lenses are used to extract the signal from the backside of the substrate. In this study the authors present a broadband bow-tie slot antenna with a tuning stub which is diced and mounted on a ground plane to alleviate the substrate effects. Here, the large dielectric constant substrate around the antenna conductor is removed. In addition, the ground plane underneath the diced substrate acts as a reflector and, ultimately, the antenna radiates to the air-side direction. Antenna integration with RTD oscillators is described in this study as well. Two-port bow-tie slot antennas were designed and characterised and showed the suitability of integration with power combining RTD oscillator circuits which are based on mutual coupling. The antennas were fabricated using electron beam lithography on a semi-insulating InP substrate. Simulated and measured bandwidth almost extends the entire frequency range 230–325  GHz. Simulations shows air-side radiation pattern and antenna gain of around 11  dB at 280  GHz. Simulations also show that the antenna may be fed with a 50-Ω or 30-Ω feed line, i.e. suitable feed lines, without compromising its performance which may prove beneficial for optimum loading of RTD oscillators

Antibacterial activity of Commiphora molmol (Myrrha) against the periodontal pathogen, Aggregatibacter actinomycetemcomitans

The exogenous pathogen Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) is most frequently involved in periodontitis and other systemic diseases. The treatment of these infections involves antibiotic therapy with Amoxicillin being the most popular antibiotic against A. actinomycetemcomitans but now, the drug is not 100% effective due to the development of 0-84% antibiotic resistance. The present study aimed to determine antibacterial activity of Commiphora molmol (Myrrha) against the periodontal pathogen, Aggregatibacter actinomycetemcomitans. In detail, the strain LIU1239 of Aggregatibacter actinomycetemcomitans was used where the plasmid pVJT128 is used for transposon mutagenesis and the Escherichia coli strain MV10Nal (stock # LIU4). The slow growing mutant, LIU 1380 strain was obtained by transposon mutagenesis and was confirmed to be slow growing by sequential streaking on AAGM plates for three passages. The experiment was mainly designed to show the antimicrobial activity of 20% Myrrha oil in AAGM and phosphate buffer. In nutrient rich AAGM, the oil took twenty hours to kill most cells of both strains, and at 5 hours, both strains were killed to the same extent. However, in nutrient-free phosphate buffer Myrrha killed the small colony mutant much faster than the wild type cells. For the very first time, the current study reported a marvelous antibacterial activity of Myrrha oil against A. actinomycetemcomitans in the nutrient-free medium. The findings showed that Myrrha oil extract can kill both growing and non-growing bacteria effectively. This antibacterial activity increases with the increasing concentration of oil up to 0.3 % against LIU1142, LIU 1239, and 1380 mutant. The use of Myrrha against A. actinomycetemcomitans could be a promising treatment to combat periodontitis and other bacterial infections

Novel Tunnel Diode Oscillator Power Combining Circuit Topology Based on Synchronisation

Devices with negative differential resistance (NDR) regions in their current-voltage (I-V) characteristics such as tunnel diodes (TD) and resonant tunneling diodes (RTDs) have been used for realizing high frequency oscillators. In this paper, a new power combining technique is presented which combines output power through synchronisation of two coupled tunnel diode oscillators. The measured output power of the two synchronised tunnel diode oscillators realized in microstrip hybrid technology was -6.72 dBm at 716.2 MHz, while that of single tunnel diode oscillator was -9.09 dBm at 575.7 MHz. The circuit topology proposed in this paper can be utilized to realize high power and high frequency RTD terahertz sources

Backstepping Control and Transformation of Multi-Input Multi-Output Affine Nonlinear Systems into a Strict Feedback Form

This dissertation presents an improved method for controlling multi-input multi-output affine nonlinear systems. A method based on Lie derivatives of the system\u27s outputs is proposed to transform the system into an equivalent strict feedback form. This enables using backstepping control approaches based on Lyapunov stability and integrator backstepping theory to be applied. The geometrical coordinate transformation of multi-input multi-output affine nonlinear systems into strict feedback form has not been detailed in previous publications. In this research, a new approach is presented that extends the transformation process of single-input single-output nonlinear. A general algorithm of the transformation process is formulated. The research will consider square feedback linearizable multi-input multi-output systems where the number of inputs equals to the number of outputs. The preliminary mathematical tools, necessary and sufficient feedback linearizability conditions, as well as a step-by-step transformation process is explained in this research. The approach is applied to the Western Electricity Coordinating Council (WECC) 3-machine nonlinear power system model. Detailed simulation results indicate that the proposed design method is effective in stabilizing the WECC power system when subjected to large disturbances

Series coupled resonant tunneling diode oscillators for terahertz applications

A series of resonant tunneling diode oscillators with frequencies up to W-band and output power around one milliwatt are presented. To our knowledge, the 75.2 GHz RTD oscillator with -0.2 dBm output power is the highest power reported. The technique demonstrated here shows the great potential to scale up the design to terahertz frequencies. Jue Wang, Khalid Alharbi, Afesomeh Ofiare, Ata Khalid, Liquan Wang, David Cumming and Edward Wasig

THz Electronics for Data Centre Wireless Links - the TERAPOD Project

This paper presents an overview of the terahertz (THz) resonant tunneling diode (RTD) technology that will be used as one of the approaches towards wireless data centres as envisioned on the eU H2020 TERAPOD project. We show an example 480 gm × 680 gm THz source chip at 300 GHz employing a 4 gm × 4 gm RTD device with 0.15 mW output power. We also show a basic laboratory wireless setup with this device in which up to 2.5 Gbps (limited by equipment) was demonstrated

Slot-Ring Multiport Driven Antenna with Improved Airside Radiation for Terahertz Communications

A slot-ring multiport driven (MPD) antenna is evaluated for operation in the terahertz band with emphasis on air-side radiation on a thick Indium Phosphide (InP) substrate. Geometrical modification to the known slot-ring are made by employing a circular outer ground and a backing ground plane to focus the radiation in the airside direction. Optimization of the modified structure is made to find the optimal size of the upper ground plane. The optimal design achieves maximum directivity of 10.8 dB which is an improvement of 3 dB from the original design. Moreover, the radiation is directed in the airside direction with a front-to-back lobe ratio of 14 dB. The slot-ring antenna design is verified by fabrication at 5 GHz and achieves 10.2 dB directivity

The mechanical contact behaviour and tribology of polymer gears

Interest in using polymer gears has been growing dramatically in the last decade. Increasing understanding of their working behaviour has improved appreciation of their advantages compared to their limitations when selecting appropriate applications. However, restricted knowledge still leaves many unfulfilled areas that might benefit from their valuable advantages and control of their limitations, for example, in replacing. their metallic counterparts in more applications. Given their very different materials properties, it is important to develop bespoke design and rating methods for polymer gears, with properly validated rules, that are not mere modifications to metallic gearing rating methods. A major aim of this thesis is to provide a new deeper understanding for use when designing and rating some technologically important types of polymer gears for wider applications. Having identified an important research gap in polymer gearing theory and practice, this thesis covers mostly experimental studies involving continuously monitored wear and wear rate and microscopic evaluation of underlying tribologies. It examines the behaviour of polymer gears made of acetal, nylon (moulded and machine-cut) and polycarbonate, all common gearing materials, during and after running under different physically realistic conditions. Some modifications to test rigs uniquely designed to operate at a continually constant load enable study of surface thermal behaviour under dry and lubricated conditions and with simulations of moderate gear misalignments. In dry-running cases, gear load capacity and wear behaviour of different polymers and variations in underlying tribology all presented important relations between the gear tooth wear rate, the applied load and the tooth surface temperature. Quite similar patterns were seen under oil lubricated conditions. Typically, though, there was a nearly three-fold improvement in gear load capacity, the wear rate and gear tooth surface temperature were decreased, and SEM showed some changes in surface tribology. Finally, deliberately introduced angular misalignments between gear pairs indicated a reasonable tolerance of small but practical levels, with different tribological behaviours between the left and right sides of the tooth surfaces. A severe increase in wear rate and tooth failure arose from misalignments above 0.8ο yaw angle and 0.4ο pitch angle. After a unifying discussion, conclusions are drawn and further work is proposed for extended studies over different parameter ranges