Development of biodegradable composite micro-perforated panel made from natural fibre composites with evaluation of its acoustic and mechanical properties

Micro-perforated panel (MPP) has been widely considered as a promising alternative for sound absorption purposes. Plenty of research has been done to improve the sound absorption of MPP but no specific work highlights the material structure effect towards its sound absorption performance. MPP is mostly made from metallic or plastic materials which does not exhibits any pores or tortuous structure and therefore, material structure issue is often being eliminated from analysis. In order to study the material structure effect, alternative material must be used to fabricate MPP. Numerous research found that natural fibre possesses excellent sound absorption properties due to its porous and tortuous structure. Yet, natural fibre has low tolerance towards mechanical processing and thus binder must be incorporated to overcome this shortcoming. This thesis basically describes the development process of biodegradable composite micro-perforated panel (BC-MPP) made from natural fibre (kenaf, wood, and coconut) and polylactic acid (PLA) composites. BC-MPP samples were fabricated with different material composition percentage of natural fibre and PLA. The effect of material composition percentage, perforation ratio, perforation diameter, and air cavity thickness were investigated. The effect of material structure towards the sound absorption performance of BC-MPP sample was studied. It has been found that existence of pores and tortuous structure can indeed influence the sound absorption performance of BC-MPP sample. The sound absorption performance of BC-MPP sample was compared to conventional MPP and it has been found that BC-MPP possessed better sound absorption performance courtesy to its porous and tortuous structure. BC-MPP sample also possessed better tensile strength compared to common sound absorption panel such as medium density fibreboard, hardboard, commercial ceiling board, and plywood

Inferring waypoints in the absence of knowledge of driving style

We present an algorithm for predicting intervals which contain waypoints from a GPS trace of a multi-part trip without having access to historical data about the driver or any other aggregated data sets. We assume the driver’s driving style is not known, but that it can be approximated by one of a set of cost preferences. The method uses a set of repeated forward and backward searches along the trace, where each of the searches represents one of the driving costs. We evaluate the algorithm empirically on multi-part trips on real route maps. The algorithm selects the results of the search with the fewest number of intervals and we achieve over 95% recall on estimating waypoints while the intervals cover less than 9% of the tra

Inferring waypoints using shortest paths

We present a method for reconstructing intermediate destinations from a GPS trace of a multi-part trip, without access to aggregated statistics or datasets of previous traces. The method uses repeated forwards and backwards shortest-path searches. We evaluate the algorithm empirically on multi-part trips on real route maps. We show that the algorithm can achieve up to 97% recall, and that the algorithm degrades gracefully as the GPS traces become sparse and irregular

Static Shear Strength of Single-Lap Joint Using Eggshell-Toughened Epoxy as Adhesive Agent

Eggshells are daily food waste in every household and are disposed of in landfills, producing environmental issues, and their decomposition has generated an unpleasant odour. Eggshell powder is made of finely crushed particles and is suitably applied as a filler in thermoset polymers such as epoxy resin to improve their mechanical properties. The shear strength of toughened epoxy with eggshell powder (TEEP) is studied. Single-lap joint (SLJ) shear tests were conducted to investigate the shear strength of the SLJ bonded with different volume fractions of TEEP. For this purpose, the eggshells were dried and crushed into particles of size 150μm. The volume fraction of eggshell powder in the epoxy resin is 0%, 2.5%, 5%, and 10% by volume. The epoxy resin system was made of EPIKOTE Resin 828 and Hardener 651 with a mixing ratio of 5:2 by volume. The results show that the ultimate joint strength greatly depended upon overlap length and filler volume fractions. The improvement was up to 72.7% and 39.9%, with the longest overlap length and 10% TEEP fraction. Hence, an overlap length of 38.1 mm and a 5% eggshell volume fraction gave the ultimate optimum strength of 5.045 kN

Static Shear Strength of Single-Lap Joint Using Eggshell-Toughened Epoxy as Adhesive Agent

Eggshells are daily food waste in every household and are disposed of in landfills, producing environmental issues, and their decomposition has generated an unpleasant odour. Eggshell powder is made of finely crushed particles and is suitably applied as a filler in thermoset polymers such as epoxy resin to improve their mechanical properties. The shear strength of toughened epoxy with eggshell powder (TEEP) is studied. Single-lap joint (SLJ) shear tests were conducted to investigate the shear strength of the SLJ bonded with different volume fractions of TEEP. For this purpose, the eggshells were dried and crushed into particles of size 150μm. The volume fraction of eggshell powder in the epoxy resin is 0%, 2.5%, 5%, and 10% by volume. The epoxy resin system was made of EPIKOTE Resin 828 and Hardener 651 with a mixing ratio of 5:2 by volume. The results show that the ultimate joint strength greatly depended upon overlap length and filler volume fractions. The improvement was up to 72.7% and 39.9%, with the longest overlap length and 10% TEEP fraction. Hence, an overlap length of 38.1 mm and a 5% eggshell volume fraction gave the ultimate optimum strength of 5.045 kN

A case study of renaissance wall paintings in Granada (Spain): historical–artistic analysis, materials characterization, and state of conservation

The research carried out on the wall paintings of Hernán Pérez del Pulgar’s Palace chapel in Granada (Spain) was aimed at determining its historical–artistic, stylistic, technical, and compositional aspects. For this, a 16th century frieze and an 18th century pendentive were studied. The mineralogical, chemical, and textural characterization of the constituent materials and the study of the state of conservation of the paintings have helped to determine the pictorial technique used, identify the nature of the salts present in the paintings, and other pathologies including a dormant fungal attack. To this end, optical microscopy (OM), X-ray diffraction (XRD), Field emission scanning electron microscopy with microanalysis (FESEM-EDS), and micro-Raman spectroscopy (MRS) were used. The information obtained helps clarify important aspects of the painting technique used, laying a basis to ensure effective and suitable conservation and restoration measures on the paintings that will ensure their durability over time.AERIMPACT | Ref. CGL2012-30729EXPOAIR | Ref. P12-FQM-1889Ministerio de Ciencia e Innovación | Ref. PID2020-119838RA-I00Grupo de Investigación de Andalucía | Ref. RNM-17

The fresco wall painting techniques in the Mediterranean area from Antiquity to the present: A review

Fresco wall paintings are one of the oldest artforms in our cultural heritage, dating back to the second millennium BC. In this work, we carry out a thorough review on the evolution of the fresco wall painting technique from Antiquity to the present day. Focused on the Mediterranean area, the aim is to gather in-depth information on different technological aspects of this decorative artform such as execution pro- cedure, materials used and pictorial palette. Considering that the recognition of the pictorial technique ( a fresco, a secco, or a mezzo fresco ) is often difficult since the identification of organic binders can be a challenging issue, the assignment of well-known non-alkaline-resistant pigments to the fresco technique might not always be precise. With this in mind, this review aims to highlight the contradictions found between the bibliographical sources on the fresco technique and recent scientific studies in relation to the preparation of materials, the execution on the wall and the incompatibility of certain pigments with the alkaline environment created by this pictorial technique.Research Projects PID2020-119838RA- I00 and ED431F 2022/07Xunta de Galicia project Limpeza sostible do patrimonio pictorico: optimizacion dos procesos de ablacion laser ( ED431F 2022/07 )Spanish Science and Innovation Ministry project RYC2020-028902-ISpanish Science and Innovation Ministry project RYC2020-028902-IState Research Agency (SRA)Ministry of Science and Innovation under the Research Project PID2020-119838RA-I00Junta de Andalucía Research Group RNM179Funding for open access charge: Universidade de Vigo/CISU

American Cyber Insecurity: The growing danger of cyber attacks

This paper aims to advise American policy makers on a correct course of action regarding the advent of cyber warfare. Cyber-attacks have become ubiquitous in the 21st century and pose a direct threat to the safety of American interests abroad and domestically. Beginning with an analysis of the history and lessons from past cyber conflicts this paper moves on to proscribe a set of actions to protect American security in the 21st century. We conclude that the current legal framework for evaluating cyber-attacks needs to be re-framed in a manner more conducive to American interests.Winner of the 2014 Alona E. Evans Prize, a Duke Political Science award for the undergraduate or graduate student(s) whose paper on international law best reflects excellence in scholarshi

The fresco wall painting techniques in the Mediterranean area from Antiquity to the present: A review

Fresco wall paintings are one of the oldest artforms in our cultural heritage, dating back to the second millennium BC. In this work, we carry out a thorough review on the evolution of the fresco wall painting technique from Antiquity to the present day. Focused on the Mediterranean area, the aim is to gather in-depth information on different technological aspects of this decorative artform such as execution procedure, materials used and pictorial palette. Considering that the recognition of the pictorial technique (a fresco, a secco, or a mezzo fresco) is often difficult since the identification of organic binders can be a challenging issue, the assignment of well-known non-alkaline-resistant pigments to the fresco technique might not always be precise. With this in mind, this review aims to highlight the contradictions found between the bibliographical sources on the fresco technique and recent scientific studies in relation to the preparation of materials, the execution on the wall and the incompatibility of certain pigments with the alkaline environment created by this pictorial technique.Agencia Estatal de Investigación | Ref. PID2020-119838RA-I00Xunta de Galicia | Ref. ED431F 2022/07Agencia Estatal de Investigación | Ref. RYC2020-028902-IUniversidade de Vigo/CISU