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Conventional motion mechanisms in adaptive skins require rigid kinematic mechanical systems that require sensors and actuation devices, hence impeding the adoption of zero-energy buildings. This paper aims to exploit wooden responsive actuators as a passive approach for adaptive facades with dynamic shading configurations. Wooden passive actuators are introduced as a passive responsive mechanism with zero-energy consumption.

The study encodes the embedded hygroscopic parameters of wood through 4D printing of wooden composites as a responsive wooden actuator. Several physical experiments focus on controlling the printed hygroscopic parameters based on the effect of 3D printing grain patterns and infill height on the wooden angle of curvature when exposed to variation in humidity. The printed hygroscopic parameters are applied on two types of wooden actuators with difference in the saturation percentage of wood in the wooden filaments specifically 20% and 40% for more control on the angle of curvature and response behavior.

The study presents the ability to print wooden grain patterns that result in single and double curved surfaces. Also, printing actuators with variation in infill height control each part of wooden actuator to response separately in a controlled passive behavior. The results show a passive programmed self-actuated mechanism that can enhance responsive façade design with zero-energy consumption through utilizing both material science and additive manufacturing mechanisms.

The study presents a set of controlled printed hygroscopic parameters that stretch the limits in controlling the response of printed wood to humidity instead of the typical natural properties of wood.

This study examines solvent extract conductivity (SEC) testing, e.g., Ionograph or Omega Meter testing, which measures ionic cleanliness of printed wiring boards (PWBs). SEC has been a quality control (QC) monitor to assure product electrical reliability. Typical SEC measurements occur after wave soldered products have been solvent‐cleaned. This study concerns SEC testing on new wave soldering processes that involve no solvent cleaning, i.e., inert gas soldering with ‘no clean’ fluxes. Results show ionic residues from ‘no clean’ fluxes may have other characteristics that make QC testing for ionic cleanliness inappropriate. However, SEC may be appropriate as a process control monitor after soldering with these fluxes. An Ionograph measured SEC response for the following chemicals: NaCl, NaF, NaBr, KCl, MgCl2, CaCl2, HCl, succinic acid, malic acid, glutaric acid, adipic acid and ethylene glycol. The list includes inorganic salts, strong electrolytes, which may arise from manufacturing or PWB materials. The list also includes weak organic acids (WOAs) common to ‘no clean’ fluxes. One non‐ionic hygroscopic chemical, ethylene glycol, was studied. Ionograph response was measured via (i) direct injection of aqueous solutions and (ii) immersion of PWBs with individual chemicals as surface deposits. All ionisable compounds, including all WOAs, produced substantial SEC response. Surface conductivity was measured at 35°C/90% relative humidity (RH) with controlled amounts of the above chemicals deposited on clean PWB test circuits. Surface loadings corresponded to the molar‐ionic equivalent of 2.0 ?g/cm2 NaCl. In addition, NaCl, adipic acid and polyethylene glycol (PEG 400) were examined as a function of concentration. Several ionisable chemicals including all WOAs produced no measurable effect, i.e., surface conductivities were indistinguishable on clean and deposited specimens. Surface conductivity increased for ionic contaminants with critical RH below ∼80% and for the non‐ionic hygroscopic glycol. SEC measurements and surface conductivities were compared. The latter is more directly related to electrical reliability. Although all ionic compounds including the WOAs showed a SEC response, not all enhanced surface conductivity. Achievement of critical RH appears to be the important factor. Adipic acid required the presence of hygroscopic glycol to enhance surface conductivity. Therefore, SEC can be a misleading QC test for electrical reliability when WOA flux residues are present.

The purpose of this study is to look into the hygroscopic and tribo-mechanical properties of a polypropylene/polyamide-6 (PP/PA6) blend and a PP/PA6/Boron sesquioxide composite.

The hygroscopic behaviour of the PP/PA6 blend and PP/PA6/Boron sesquioxide composite was studied using a water contact angle goniometer in this study. To validate the hygroscopic behaviour of the blend and composite, water contact angles and surface energy of the materials were investigated. Tensile strength and hardness tests were used to determine mechanical characteristics, and tribological experiments on a pin-on-disc tribometer were used to demonstrate the friction and wear rates of dry and water-conditioned blends and composites. The melting temperature of dry and water-conditioned composites was determined using DSC analysis.

The hygroscopic effect of the PP/PA6 blend was found to be minimal in the experiment, while it was relatively dominating in the PP/PA6/Boron sesquioxide composite. Tensile strength was found to be somewhat lower in blend and composite compared to virgin PP, whereas hardness was found to be higher in both blend and composite. The composite’s tribological testing findings were fairly outstanding, with the coefficient of friction (COF) and wear rates significantly reduced due to boron sesquioxide reinforcement. The reaction between boron sesquioxide and water molecules produced boric acid, which increased the tribological characteristics of the composite even further. Following 30 days of water conditioning, the weight of the blend increased by 3.64% and the weight of the composite increased by 6.45% as compared to the dry materials. After water conditioning, tensile strength reduced by 0.8% for the blend and 14.16% for the composite. Hardness was determined to be the same in the dry state and after water-conditioning for blend but dropped 1% for composite. As compared to blend, the COF and wear resistance of composite were 15.52% and 25.16% higher, respectively. After absorbing some water, the results increased to 28.57% and 34.9%, respectively.

The mechanical and thermal behaviour of polymer composites (particularly polyamide composites) vary depending on the surrounding environment. Tests were carried out to explore the effect of water treatment on the tribo-mechanical and thermal characteristics of PP/PA6/Boron sesquioxide composite. Water treatment caused polyamides to bind with water molecules, resulting in voids in the material. The interaction between boron sesquioxide and water molecules produced boric acid, which increased the tribological characteristics of the composite.

The purpose of this paper was to study the combined effect of hygro and thermo-mechanical behavior on a plastic encapsulated micro-electro-mechanical systems (MEMS) package during the reflow process after exposed to a humid environment for a prolonged time. Plastic encapsulated electronic packages absorb moisture when they are subjected to humid ambient conditions.

Thus, a comprehensive stress model is established for a three-axis accelerometer MEMS package, with detailed considerations of fundamentals of mechanics such as heat transfer, moisture diffusion and hygro-thermo-mechanical stress. In this study, the mold compound is considered to be the most critical plastic material in MEMS package. Other plastic components of thin film materials can be disregarded due to their small sizes such as die attach and Bismaleimide Triazine (BT) core, even though they are also susceptible to moisture. Thus, only the moisture-induced properties of mold compound were obtained from the proposed experiments. From the desorption measurement after preconditioning at 85°C/85 per cent relative humidity (RH), the saturated moisture content and diffusivity were obtained by curve fitting the data to Fick’s equation. In addition, a new experimental setup was devised using the digital image correlation system together with a precision weight scale to obtain the coefficient of hygroscopic swelling (CHS) at different temperatures.

The experimental results show that the diffusion coefficient of mold compound material follows Arrhenius equation well. Also, it is shown that the CHS of mold compound increases as temperature increases. Experimentally obtained moisture properties were then used to analyze the combined behavior (thermo-hygro-mechanical) of fully saturated MEMS package during the reflow process using a finite element analysis (FEA) with the classical analogy method. Finally, the warpage and stresses inside the MEMS package were analyzed to compare the effects of hygroscopic, thermal and hygro-thermo-mechancal behaviors.

In this study, unlike the other researches, the moisture effects are investigated specifically for MEMS package which is relatively smaller in scale than conventional electronic packages. Also, as a conjugated situation, MEMS package experiences both humid and temperature during the moisture resistance test. Thus, major objective of this study is to verify stress state inside MEMS package during the reflow process which follows the preconditioning at 85°C/85 per cent RH. To quantify the stresses in the package, accurate information of material properties is experimentally obtained and used to improve modeling accuracy.

In Japan, one of the countermeasures used to avoid the symptoms of hay fever (HF) is a hygiene mask; however, a mask can cause discomfort. The authors believe that co-occurrence analysis, which has been widely in the sciences, will be valuable to this issue. The purpose of this paper is to identify problems associated with the use of hygiene masks and recommend improvements in their function and comfort. The goal of this study was to obtain information for the development of effective hygiene masks for HF sufferers and therefore, improve their quality of life.

The authors conducted a survey of university students with HF (n=1,519) to identify problems with hygiene masks. Students completed self-report questionnaires and co-occurrence analyses were used to examine the data from a holistic perspective. Moreover, technical data, relative to the problems of wearing a mask were acquired experimentally using thermal, hygroscopic, and airflow properties.

Among Japanese university students, hygiene masks were the most popular countermeasure against HF symptoms. In addition, it was found that wearing a mask was not influenced of the type of symptoms. Most problems were related to the masks’ thermal, hygroscopic, and airflow properties.

The paper proposed the use of co-occurrence analysis to analyze problems with hygiene masks. Most problems appear to be related to the thermal, hygroscopic, and airflow properties of the masks. Moreover, such phenomena have been experimentally demonstrated.

Although a UK trajectory toward zero-carbon development for all new housing by 2016 has been set, the cost of building such homes and the changes implied for current constructional culture, together with lack of fiscal incentives, makes the target very difficult to achieve. Moreover, the recent governmental clarification of the definition of zero-carbon housing may make it impossible. This paper proposes a prototype construction (see also the associated paper in this issue) and examines in detail both the constructional and cost barriers to eliminating carbon emissions from tightly limited total thermal and electrical consumption targets (not more than 70 kWh/m2). Having established generous access to sunlight and daylight as prerequisites, a related health issue is air quality, especially with air-tight construction. While thermal and hygroscopic capacity can mediate between quality and efficiency, current norms for Scottish housing are notably poor in both respects. A key aim is to assess whether specification for a ‘low-carbon house’ can be cost effective. An analysis is undertaken to asses the increased cost associated with integration of energy efficient measures in the proposed prototype model. The specification of the building envelope and associated renewable technologies are addressed with reference to their cost implication on the overall build cost. Finally potential governmental incentives are proposed to not only meet the 2016 target, but also to promote enthusiasm by the end user. The paper concludes that low-carbon and zero-carbon scenarios would require radical changes of funding/fiscal and building cultures.

Discusses the causes of damp following the insertion of a remedial damp‐proof course and the methods which can be used to detect and prevent it. Details hygroscopic and capillary moisture, the components of the total moisture content of masonry and the uses of a moisture profile with which to measure this. Explores electrical and carbide moisture meters, explaining the pros and cons of each. Reports on alleged failures and reported causes of damp, discussing problems with replastering, condensation and penetrating damp, surface condensation, misreading of signals, bridging. Suggests that the majority of dampness problems can be resolved by undertaking a logical programme of investigation and elimination.

Many Japanese hay fever (HF) sufferers wear a hygienic face mask to prevent pollen inhalation, but most find it very uncomfortable. The purpose of this paper is to identify the problems associated with mask wearing through repeated surveys. This information can be used in the improved design of a hygienic face mask that can be worn without discomfort by HF sufferers.

In 2009 (n=1,519), 2012 (n=2,994), and 2015 (n=3,213), repeated surveys of university students were conducted. HF sufferers were queried regarding symptoms, countermeasures, and problems associated with wearing a hygienic face mask. Holistic perspectives for each year were obtained by a co-occurrence analysis of the aggregated data. The triplet co-occurrence of specific problems was compared among the surveys using the χ² test. Temporary and contemporary co-occurrence relationships were also determined.

Most Japanese university students with HF wore a hygienic face mask. In each survey, the most common problems associated with mask use were related to its thermal, hygroscopic, and air-flow properties. Contemporary problems with co-occurrence relationships were “humidity,” “breathing difficulty,” and “mist over eyeglasses” for males and, “humidity,” “breathing difficulty,” and “make-up coming off” for females.

The results of this study will contribute to improving hygienic face mask design. The co-occurrence of contemporary problems related to mask use was identified by comparing the results obtained in each year. The thermal, hygroscopic, and air flow properties of the mask cause these problems, and the air gap between the mask and the wearer’s face influences the inherent physical properties of the mask. To measure the air gap, a suitable hydrostatic pressure-balanced experimental method was applied, and the data were demonstrated experimentally.

This paper aims to investigate the effect of no-clean flux chemistry with various weak organic acids (WOAs) as activators on the corrosion reliability of electronics with emphasis on the hygroscopic nature of the residue.

The hygroscopicity of flux residue was studied by quartz crystal microbalance, while corrosive effects were studied by leakage current and impedance measurements on standard test boards. The measurements were performed as a function of relative humidity (RH) in the range from 60 to ∼99 per cent at 25°C. The corrosiveness of solder flux systems was visualized by the ex situ analysis using a gel with tin ion indicator.

The results showed that the solder flux residues are characterized by different threshold RH, above which a sudden increase in direct current leakage by 2–4 orders of magnitude and a significant reduction in surface resistance in the impedance measurements were observed.

The findings are attributed to the deliquescence RH of the WOA(s) in the flux and chemistry of water-layer formation. The results show the importance of WOA type in relation to its solubility and deliquescence RH on the corrosion reliability of printed circuit boards under humid conditions.

The classification of solder flux systems according to IPC J-STD-004 standard does not specify the WOAs in the flux; however, ranking of the flux systems based on the hygroscopic property of activators would be useful information when selecting no-clean flux systems for electronics with applications in humid conditions.

A new aramid base material for use in laminates to be applied to advanced surface mount technology was developed. A new fibre based on PPDETA (Poly‐p‐phenylene/3,4'‐diphenylether terephthalamide) was found to have negative thermal and hygroscopic expansion coefficients, low ionic impurities and high affinity to epoxy and polyimide resins. The fibre was processed into fabrics and papers to be used as a base material for printed circuit boards for advanced surface mount technology. Impregnation with a new epoxy resin with high purity and high temperature resistance implemented the development of a new laminate with minimal electromigration and high dimensional stability. Thus, a new laminate was developed to be used for LCCC, PGA, COB, TAB, Flip‐Chips and other advanced surface mount technologies. Reliability of the laminate to electromigration between surface conductors, between plated‐through barrels, and between opposed conductors was found to be one of the highest available today. These types of behaviour were related to the high purity and high temperature resistance of both the reinforcement material and the resin. The short life of through‐hole plating in thermal shock was improved by the application of a new plating technology. Application to multilayer boards and laminates with a low dielectric constant is also being investigated.