Phosphor-LED-Based Wireless Visible Light Communication (VLC) and Its Applications

In this chapter, we review our recent works on the phosphor white‐light light‐emitting diode (LED)-based wireless visible light communication (VLC) and its applications. This chapter is divided into two sections for introduction. In the first section, in order to enhance the transmission rate in phosphor-LED VLC system, we propose and demonstrate a novel multiband orthogonal-frequency-division-multiplexed (OFDM) modulation format for capacity enhancement. Based on the proposed scheme, various bands of OFDM signals are employed to different LED chips of the LED luminary; it can prevent the power fading and nonlinearity effects of transmission signal. Therefore, the maximum enhanced percentage of VLC data rate is 41.1%. In the second section, we also demonstrate a 71.3–148.4 Mbps phosphor-LED wireless VLC system at the free space transmission distance between 1.4 and 2.1 m. Finally, to understand and demonstrate the real-time LED VLC transmission, a commercial OFDM-based digital signal processor (DSP) is used in the LED transmitting side and client side, respectively. Therefore, the proposed real-time half-duplex VLC system can complete around 70 Mbps downstream and upstream traffic throughputs, in a free space transmission distance of 2 m long for practical in-home illumination and smart city applications

Utilization of Reflective Semiconductor Optical Amplifier (RSOA) for Multiwavelength and Wavelength-Tunable Fiber Lasers

In this chapter, there are three sections to demonstrate the reflective semiconductor optical amplifier (RSOA)-based fiber laser architectures for multiwavelength and wavelength-tunable operations. In the first section, we introduce an L-band multiwavelength laser by utilizing a C-band RSOA with a linear cavity, which is produced by a polarization controller (PC), an optical coupler (OCP), and a reflected fiber mirror (RFM). In the proposed RSOA laser scheme, two to seven wavelengths could be lased and created simultaneously in the L-band range, while the RSOA operates at various bias currents

The management of municipal solid waste in Hong Kong : a study of civic engagement strategies

published_or_final_versionPolitics and Public AdministrationMasterMaster of Public Administratio

A Simple Fiber Bragg Grating-Based Sensor Network Architecture with Self-Protecting and Monitoring Functions

A novel fiber Bragg grating (FBG)-based passive sensor architecture, which can be used to protect the fiber cut and monitor the multiple sensors simultaneously, is proposed and experimentally demonstrated. Here, we employ a wavelength-tunable erbium-doped fiber (EDF) laser scheme with 25 km cavity length acting as the detecting light source in central office (CO). Each FBG sensor, serving as a feedback element, is used in proposed sensor architecture. By tuning the tunable bandpass filter (TBF) placing inside cavity to match the corresponding Bragg wavelength of FBG over the amplification bandwidth, we can retrieve the related wavelength lasing for the FBG sensing and monitoring simultaneously. Moreover, the survivability and capacity of the passive FBG sensor architecture can be also enhanced

Is Student Participation in School Governance a “Mission impossible”?

The civic mission of schools in nurturing political literature, critical thinking and participatory citizens has always been played down in Hong Kong schools. On one hand, teaching civic education has never been ranked high in the education agenda. On the other hand, because of the conservative nature of schools, students are rarely encouraged to participate in school governance for the enhancement of their citizenship development. Funded by the General Research Fund (GRF) in Hong Kong, the authors conducted a quantitative survey on students’ participation in school governance and their citizenship development in 2013 to explore 1) students’ conception of “good citizens”; 2) the level and scope of student participation in school governance; and 3) the facilitating and hindering factors influencing student participation. This paper is a report on the simple statistical results of the survey findings. With reference to Westheimer and Kahne’s typologies, the findings revealed that the students had an eclectic understanding of citizenship, with higher scores for Personally Responsible Citizen and lower scores for Participatory, Justice Oriented and Patriotic Citizen, reflecting a conservative orientation. Concerning the implementation of school civic mission through student participation in school governance, it was found that students were rarely allowed to engage in important school matters, such as formulation of school rules and discussion of the school development plan. Our findings also revealed that schools were more inclined to inform students and consult them rather than confer real participation and powers to them. The paper concludes that the current practice of student participation in school governance does not facilitate the nurturing of active participatory citizens, particularly of a Justice Oriented nature, and this is urgently needed for the democratic development of Hong Kong

Measurement of Organic Chemical Refractive Indexes Using an Optical Time-Domain Reflectometer

In this investigation, we propose and experimentally demonstrate a method for measuring the refractive index (RI) of liquid organic chemicals. The scheme is based on a single-mode fiber (SMF) sensor and an optical time-domain reflectometer (OTDR). Here, due to the different reflectance (R) between the SMF and organic liquid chemicals, the reflected power level of the backscattering light (BSL) measured by the OTDR would be different. Therefore, we can measure the RI of chemical under test via the measured BSL level. The proposed RI sensor is simple and easy to manipulate, with stable detected signals, and has the potential to be a valuable tool for use in biological and chemical applications

Lupus nephritis in Chinese children--a territory-wide cohort study in Hong Kong

We report a multicenter study of Chinese children in Hong Kong with systemic lupus erythematosus (SLE) nephritis. Children were included if: they fulfilled the ACR criteria, had significant proteinuria or casturia, were Chinese and younger than 19 years and had been diagnosed with SLE between January 1990 and December 2003. Investigators in each center retrieved data on clinical features, biopsy reports, treatment and outcome of these patients. There were 128 patients (eight boys, 120 girls; mean age: 11.9+/-2.8 years). About 50% presented with multisystem illness and 40% with nephritic/nephrotic symptoms. Negative anti-dsDNA antibodies were found in 6% of the patients. Renal biopsy revealed WHO Class II, III, IV and V nephritis in 13 (10%), 22 (17%), 69 (54%) and 13 (10%) patients, respectively. The clinical severity of the nephritis did not accurately predict renal biopsy findings. The follow-up period ranged from 1 to 16.5 years (mean+/-SD: 5.76+/-3.61 years). During the study five patients died (two from lupus flare, one from cardiomyopathy, two from infections). Four patients had endstage renal failure (ESRF) (one died during a lupus flare). All deaths and end-stage renal failure occurred in the Class IV nephritis group. Chronic organ damage was infrequent in the survivors. The actuarial patient survival rates at 5, 10 and 15 years of age were 95.3, 91.8, and 91.8%, respectively. For Class IV nephritis patients, the survival rates without ESRF at 5, 10, and 15 years were 91.5, 82.3 and 76%, respectively. The survival and chronic morbidity rates of the Chinese SLE children in the present study are comparable to those of other published studies.postprin