Architectural Engineering

Infrared spectroscopy experiments in the 15-to-149 THz spectral regime were performed in the transmission mode on a thin film of bulk Parylene-C polymer at normal incidence. The relative permittivity of bulk Parylene-C polymer in this regime was modeled as comprising a frequency-independent term as well as contributions from 32 Lorentz oscillators. A leastsquares minimization algorithm and a hybrid genetic algorithm were used to determine the frequency-independent term as well as all parameters characterizing the Lorentz oscillators from the measured transmittance spectrum itself.

Columnar microfibrous multifunctional metamaterials (mimumes) of Parylene-C polymer were fabricated by a modification of conventional chemical vapor deposition (CVD) and investigated for mechanical, dielectric, and wetting characteristics. For each columnar mimume, a vapor of reactive Parylene-C monomers was collimated and obliquely directed towards a planar wafer at an angle  v with respect to the wafer plane in a low-pressure chamber. The columnar mimume developed as microfibers grew at an angle  with respect to the planar wafer. An 'increasing and intermittently constant' kind of dependence of microfiber inclination angle on the monomer deposition angle  v was found. This dependence of on  v is classified into four regimes of two different types and is reminiscent of Geneva gear mechanism. The crystal structure file of Parylene-C polymer was constructed and X-ray diffraction (XRD) experiments in reflection mode revealed the presence of three crystal planes in columnar mimumes in addition to the single plane found in a (highly oriented) bulk Parylene-C film. Columnar mimumes were found to be less crystalline than bulk films, and the XRD intensities of the columnar mimumes were found to reflect the four regimes of the vs  v plot. Resonance frequencies in infrared absorbance spectra of the columnar mimumes were found to be identical indicating the similarity in atomic bonding for all monomer deposition angles. Analysis of water-wetting characteristics revealed that the columnar mimumes have higher contact-angle hysteresis than the bulk film. The morphologically significant plane (MSP) of a columnar mimume exhibits higher static hydrophobicity than the vertical plane orthogonal to the MSP, but an isotropic nature was observed for the upper and lower limits of static hydrophobicity. By an appropriate choice of the monomer deposition angle, both static hydrophobicity as well as water wettability can be maximized.

Silicon-based CMOS material set is rather restrictive for the realization of the full potential of NEMS/MEMS and, hence, a wide spectrum of new material compositions and morphologies are being explored. Because of its extensive applications in electronic and medical devices as well as because of its chemical inertness and thermal stability, a polymer called Parylene C was used to grow microfibrous thin films using physicochemical vapor deposition in a PDS2010 Parylene-C labcoater on n-type Si or brass substrates. The thin films are assemblies of parallel microfibers tilted at an angle χ with respect to the substrate plane. During deposition, a collimated vapor flux of Parylene C was directed at an angle χ v with respect to the same plane. Values of χ v used were 10°, 25°, 45°, 60°, and 90°. Both χ and the mass density increase with increasing χ v . Using Parylene-C microfibrous thin films as the dielectric layers in metal-insulator-semiconductor (MIS) and metal-insulator-metal (MIM) capacitor structures, we were able to study their dielectric properties. The dependence of the "effective" relative permittivity  eff on χ v was observed to be controlled by the amplitude of the applied AC signal, and  eff was found to decrease with increasing signal frequency. The MIS and MIM leakage current was used to study the dependence of hopping conduction on both the frequency and the temperature. These observations were interpreted relative to series/parallel networks of miniature resistors and capacitors. Also, we undertook a dynamic mechanical analysis, whereby a Parylene-C microfibrous thin film was clamped at two ends and subjected to cyclic loading. The storage and the loss moduli were measured as functions of frequency, in the frequency range 5 to 200 Hz,

The acoustic scattering characteristics of ∼10 µm-long microfibers of Parylene C embedded in water were investigated, towards the eventual goal of designing polymeric sculptured thin films for biomedical applications. The chosen microfibers were upright circular-cylindrical, slanted circular-cylindrical, chevronic, and helical in shape. A combination of numerical and analytical techniques was adopted to examine the scattering of plane waves in a spectral regime spanning the lower few eigenfrequencies of the microfibers. Certain maximums in the spectrums of the forward and back scattering efficiencies arise from the phenomenon of creeping waves. The same phenomenon affects the total scattering efficiency in some instances. The spectrums of all efficiencies exhibit the geometric symmetry of a microfiber in relation to the direction of propagation of the incident plane wave. Similarities in the shapes of the slanted circular-cylindrical and the chevronic microfibers are reflected in the spectrums of their scattering efficiences. A highly compliant microfiber has shorter and broader peaks than a less compliant microfiber in the spectrums of the total scattering efficiency. The proper design of polymeric sculptured thin films will benefit from the knowledge gained of the directions of maximum scattering from individual microfibers.

Microfibrous thin films (µFTFs) of Parylene C are deposited to a thicknesses of about 100 µm by physicochemical vapor deposition with the intention of determining the sound absorption of these films in the lower audible frequency range. The objective is to determine the sound absorption by the µFTFs by using dynamic loading experiments. The µFTFs were subjected to cyclic elastic loads in the frequency range of 5 to 200 Hz over a temperature range of 25 to 50 • C to determine their dynamic moduli and thus extract the Parylene-C µFTFs sound absorption properties. The absorption coefficient of microfibrous Parylene-C is found to be weakly dependent on temperature, however it increases with increasing frequency. Peaks in the spectra of the absorption coefficient were attributed to resonant coupling between incident sound waves and vibrating microfibers.

Columnar microfibrous thin films (µFTFs) of the polymer Parylene C with different microfiber inclination angles were fabricated using a physicochemical vapor deposition process whereby a collimated flux of hot monomers is obliquely directed towards a planar substrate. Each µFTF was then subjected to cyclic elastic loading in one of two orthogonal directions lying wholly in the substrate plane: either (i) normal or (ii) parallel to the morphologically significant plane of the µFTF. Dynamic storage and loss moduli were determined in the 1 to 80 Hz frequency range for temperatures between −40 • C and 125 • C. For all the columnar µFTFs, the storage and loss moduli for normal loading did not exceed their counterparts for parallel loading. All the columnar µFTFs were found to be softer than a bulk film of Parylene C. In both bulk and columnar forms, Parylene C was found to be rheologically not simple.

In the aerospace industry, every minute of downtime because of equipment failure impacts operations significantly. Therefore, efficient maintenance, repair and overhaul processes to aid maximum equipment availability are essential. However, scheduled maintenance is costly and does not track the degradation of the equipment which could result in unexpected failure of the equipment. Prognostic Health Management (PHM) provides techniques to monitor the precise degradation of the equipment along with cost-effective reliability. This article presents an adaptive data-driven prognostics reasoning approach. An engineering case study of Turbofan Jet Engine has been used to demonstrate the prognostic reasoning approach. The emphasis of this article is on an adaptive data-driven degradation model and how to improve the remaining useful life (RUL) prediction performance in condition monitoring of a Turbofan Jet Engine. The RUL prediction results show low prediction errors regardless of operati...

This research investigates the acoustical characteristics of Al-Madinah Holy Mosque. Extensive field measurements were conducted in different locations of Al-Madinah Holy Mosque to characterize its acoustic characteristics. The acoustical characteristics are usually evaluated by the use of objective parameters in unoccupied rooms due to practical considerations. However, under normal conditions, the room occupancy can vary such characteristics due to the effect of the additional sound absorption present in the room or by the change in signal-to-noise ratio. Based on the acoustic measurements carried out in Al-Madinah Holy Mosque with and without occupancy, and the analysis of such measurements, the existence of acoustical deficiencies has been confirmed. Keywords—Worship sound, Al-Madinah Holy Mosque, mosque acoustics, speech intelligibility.

Many residential buildings in hot climates use a huge amount of energy to run the air conditioning in order to maintain comfortable conditions for the occupants. This study of a domestic building in Libya used detailed monitoring and analysis of the measured data with a view to devising a strategy for reducing energy consumption and carbon emissions.

As a result of increasing population and buildings construction in Saudi Arabia, the demand for electricity is growing rapidly. There should be a greater focus on buildings in the kingdom and several methods should be applied in order to reduce energy consumption and create a lower carbon economy as residential buildings account for about 70 percent of the total consumption. Saudi Arabia therefore urgently needs to develop residential buildings which use less energy and are more environmentally-friendly. This study investigates the recent situation of Saudi residential buildings in terms of energy and building materials, using case studies. The main aim of this study is to identify suitable strategies and propose a number of recommendations that are useful in developing residential buildings in the Kingdom of Saudi Arabia. This paper shows the importance of selecting the right, locally available, construction materials for the external wall and thermal insulation in reducing energy consumption for the cooling load, by 59% after using the most appropriate construction materials for Saudi climate. Several methods were used in this research including