Multi-wavelength fiber laser with erbium doped zirconia fiber and semiconductor optical amplifier

Multi-wavelength hybrid fiber lasers are demonstrated in both ring and linear cavities using a fabricated Erbium-doped Zirconia fiber (EDZF) and semiconductor optical amplifier (SOA) as gain media. In both configurations, the a fiber loop mirror, which is constructed using a 3 m long polarization maintaining fiber (PMF) and a polarization insensitive 3dB coupler is used as a comb filter for the fiber laser. In the ring cavity, 10 simultaneous lines with peak power above -26 dBm is obtained at 1550 nm region. This is an improvement compared to the linear cavity configuration which has only 5 simultaneous lines observed from wavelength 1556.1 nm to 1563.0 nm with the peak power above -40 dBm. Both hybrid lasers has a constant line spacing of 1.7 nm, which is suitable for wavelength division multiplexing and sensing applications and shows a stable operation at room temperature

Causative failure factors of communications management in mixed-use development projects in Malaysia

Construction delay has been a persistent challenge for the Malaysian construction industry. This has resulted in many issues, including public complaints, government loss of reputation and income and a decline in the gross domestic product output of the industry. Furthermore, the construction industry is a complex business with several stakeholders continually sharing information. Hence, ensuring project success has to be the utmost important task of a project manager. Often the construction industry is marred by high cases of delays, overruns, poor quality, health and safety issues, emissions and sustainability issues as a result of ineffective communication practices. Therefore, this paper aims to examine causative failure factors of communications management in mixed-use development projects in Malaysia. Based on the literature review, 11 factors and 44 items were identified. These factors and items were evaluated by 141 respondents from the Malaysian construction industry. Data analysis was done using SPSS 23.0. This study found that the most critical causative failure factor is team meeting discussions. The respondents believe that there is lack of stakeholder cooperation due to poor representation during the discussions, which also reflects the inadequacy of mutual respect, confidence and trust among stakeholders. As a recommendation, frequent team meeting discussions provide a platform for effective information exchange, thus help to reduce mixed-use project failures in Malaysia

Fabrication, Characterization, and Optimization of CdS and CdSe Quantum Dot-Sensitized Solar Cells with Quantum Dots Prepared by Successive Ionic Layer Adsorption and Reaction

CdS and CdSe quantum dot-sensitized solar cells (QDSSCs) were used for the study of determining the optimum preparation parameters that could yield the best solar cell performance. The quantum dots (QDs) were coated on the surface of mesoporous TiO2 layer deposited on FTO substrate using the successive ionic layer adsorption and reaction (SILAR) method. In this method the QDs are allowed to grow on TiO2 by dipping the TiO2 electrode successively in two different solutions for predetermined times. This method allows the fabrication of QDs in a facile way. Three preparation parameters that control the QD fabrication were investigated: concentration of precursor solutions, number of dipping cycles (SILAR cycles), and dipping time in each solution. CdS based QDSSC showed optimum performance when the QDs were prepared from precursor solutions having the concentration of 0.10 M using 4 dipping cycles with the dipping time of 5 minutes in each solution. For CdSe QDSSC, the optimum performance was achieved with QDs prepared from 0.03 M precursor solutions using 7 dipping cycles with 30 s dipping time in each solution. The QDs deposited on TiO2 surface were characterized using UV-vis absorption spectroscopy, FESEM, and TEM imaging

A Suitable Polysulfide Electrolyte for CdSe Quantum Dot-Sensitized Solar Cells

A polysulfide liquid electrolyte is developed for the application in CdSe quantum dot-sensitized solar cells (QDSSCs). A solvent consisting of ethanol and water in the ratio of 8 : 2 by volume has been found as the optimum solvent for preparing the liquid electrolytes. This solvent ratio appears to give higher cell efficiency compared to pure ethanol or water as a solvent. Na2S and S give rise to a good redox couple in the electrolyte for QDSSC operation, and the optimum concentrations required are 0.5 M and 0.1 M, respectively. Addition of guanidine thiocyanate (GuSCN) to the electrolyte further enhances the performance. The QDSSC with CdSe sensitized electrode prepared using 7 cycles of successive ionic layer adsorption and reaction (SILAR) produces an efficiency of 1.41% with a fill factor of 44% on using a polysulfide electrolyte of 0.5 M Na2S, 0.1 M S, and 0.05 M GuSCN in ethanol/water (8 : 2 by volume) under the illumination of 100 mW/cm2 white light. Inclusion of small amount of TiO2 nanoparticles into the electrolyte helps to stabilize the polysulfide electrolyte and thereby improve the stability of the CdSe QDSSC. The CdSe QDs are also found to be stable in the optimized polysulfide liquid electrolyte

A simple load sensor based on a bent single-mode–multimode–single-mode fiber structure

A load sensor is demonstrated using a single-mode-multimode-single-mode (SMS) fiber structure, which is sandwiched between two CR-39 plastic polymer plates. A larger effective transverse strain can be achieved when the distance, D2, between the stage and the edge of the multimode fiber is larger. A higher sensitivity is obtained when D2 = 7 cm with a value of −0.0102 nm/mN, as compared to −0.0027 nm/mN when D2 = 3 cm. In contrast, an FBG integrated in a similar manner has shown an indiscernible change in the wavelength shift as compared to that produced by the SMS device. The result indicates that the proposed SMS device is suitable for sensing a small load or transverse strain with a reasonably high sensitivity

Phthaloylchitosan-Based Gel Polymer Electrolytes for Efficient Dye-Sensitized Solar Cells

Phthaloylchitosan-based gel polymer electrolytes were prepared with tetrapropylammonium iodide, Pr 4 NI, as the salt and optimized for conductivity. The electrolyte with the composition of 15.7 wt.% phthaloylchitosan, 31.7 wt.% ethylene carbonate (EC), 3.17wt.% propylene carbonate (PC), 19.0 wt.% of Pr 4 NI, and 1.9wt.% iodine exhibits the highest room temperature ionic conductivity of 5.27 x 10 -3 S cm -1. The dye-sensitized solar cell (DSSC) fabricated with this electrolyte exhibits an efficiency of 3.5% with.. SC of 7.38mAcm -2,.. OC of 0.72V, and fill factor of 0.66. When various amounts of lithium iodide (LiI) were added to the optimized gel electrolyte, the overall conductivity is observed to decrease. However, the efficiency of the DSSC increases to a maximum value of 3.71% when salt ratio of Pr 4 NI : LiI is 2 : 1. This cell has.. SC,.. OC and fill factor of 7.25mAcm -2, 0.77V and 0.67, respectively

Exploring opportunities of adopting biophilic cities concept into mixed-use development project in malaysia

Mixed-use development project in urban area emerged to cater the increase of population in the region. Due to rapid urbanisation, many research recommended the engagement of human with nature in cities development, including the mixed-use development project since nature and human are holistically created to complement each other. This is where the United Nation (UN) under its sustainable development programme has established 17 development goals that amongst all cover both sustainable cities and communities. This shows the urgency of having cities that best fit human nature. However, although many mixed-use development projects were constructed with senses of nature, many of these projects are harmful to environment as they are unable to sustain the natural habitat as well as human needs. Hence, there are many attempts to connect human with nature in Malaysia via sustainable cities and green cities concepts although no specific guidelines on these have been established. Recently, emerged the term biophilic cities, a new concept combining sustainable and resilient cities, which are also seen as the panacea to these mixed-use development project issues despite the efforts done via the former concepts of sustainable and green cities alone. Generally, biophilic cities resemble green cities with a few enhanced greener criteria that affiliate human to nature as opposed to green and sustainable cities that merely bring nature to human. Therefore, this paper aims at investigating the elements of biophilic cities that can be adopted for mixed-use development project in Malaysia. Via systematic literature review, this paper listed the criteria of biophilic cities from previous studies, which are then used in designing the questionnaires distributed to 173 construction players in the mixed-use development projects in Malaysia. It is found that biophilic cities encompass four main criteria that are important to be adopted in mixed-use development project in Malaysia, namely "building", "block", "street" and "neighbourhood", with a total of eight design elements. As biophilic cities are closer to human needs and environment whilst able to manage the rapid urbanisation and increased world population that is meant to be tackled by the mixed-use development project, construction players should start to consider adopting the biophilic cities concept in their mixed-use development project in Malaysia