Fluorescence lidar monitoring of historic buildings

Laser-induced fluorescence spectra detected with high-spectral-resolution lidar on the facades of the Baptistery and the Cathedral in Parma are presented and discussed. The data show fluorescence features that are due to the stone materials that constitute the coating of the monuments and to photosynthetically active colonizations on their surfaces. This underlines the feasibility of a remote fluorescence analysis of historic facades. The data were also compared with the fluorescence lidar spectra obtained from similar lithotypes, sampled either in historic extraction areas or in sites exploited recently. The results open good prospects for spectral characterization of historic materials and identification of their provenance.     

Versatile mobile lidar system for environmental monitoring

A mobile lidar (light detection and ranging) system for environmental monitoring is described. The optical and electronic systems are housed in a truck with a retractable rooftop transmission and receiving mirror, connected to a 40-cm-diameter vertically looking telescope. Two injection-seeded Nd:YAG lasers are employed in connection with an optical parametric oscillator-optical parametric amplification transmitter, allowing deep-UV to mid-IR wavelengths to be generated. Fast switching that employs piezoelectric drivers allows multiwavelength differential absorption lidar for simultaneous measurements of several spectrally overlapping atmospheric species. The system can also be used in an imaging multispectral laser-induced fluorescence mode on solid targets. Advanced LabVIEW computer control and multivariate data processing render the system versatile for a multitude of measuring tasks. We illustrate the monitoring of industrial atmospheric mercury and hydrocarbon emissions, volcanic sulfur dioxide plume mapping, fluorescence lidar probing of seawater, and multispectral fluorescence imaging of the facades of a historical monument.     

Detection and characterization of biodeteriogens on stone cultural heritage by fluorescence lidar

Biodeteriogens are an important cause of the weathering of a monument, particularly those made of stone, and their detection at an early stage of development helps to protect the monument from deterioration. Frequent mapping of biodeteriogen accumulation is therefore highly necessary. The use of fluorescence lidar for this purpose was introduced in 1995 and has been developed in subsequent years. Three main aspects emerged during this research: the possibility of discriminating between different biodeteriogen strains, the minimum detectable quantity of biodeteriogens, and the control of the efficiency of biocide treatments. We describe the results of a laboratory experiment devoted to clarifying these three aspects of biodeteriogen monitoring by means of fluorescence lidar.     

易碎岩石大粒径石料开采爆破关键参数研究

随着外海建港项目的增多,在易碎岩石中集中爆破生产大粒径规格石料成为一个难题。通过分析应力波和爆炸气体对裂隙走向和长度的影响,提出了增大最小抵抗线和填塞长度、减小孔间距的单排孔开采方案,以及关键参数的计算公式,并多次得到工程实践的验证。     

局部外形特征对高层建筑立面上围护结构风荷载的影响

基于一外形复杂的高层建筑刚性模型表面压力测量风洞试验,对高层建筑立面上测点的最不利风压系数进行了研究,分析了局部外形特征对高层建筑立面上围护结构风荷载的影响。试验结果表明,最不利正风压系数不受建筑立面局部外形特征的影响,可以基于来流湍流特征用准定常理论近似预测。最不利负风压系数与尾流分离有关,受建筑局部外形特征的影响较大,平直立面上的小,弧形立面上的大。这些结论为高层建筑围护结构的设计提供了参考。     

Diamond wire cutting: A methodology to evaluate stone workability

The economic relationship between the companies that produce multi-wire cutting machines and the stone slab producers is based on the classification of the rocks, mainly determined by the users themselves, that take into account the relative ease of cutting. This classification is principally based on the cutting speeds (feed and peripheral), which are obviously correlated with stone properties and cannot be evaluated before the working phase. The aim of this study is to use inexpensive and simple tests to make, before cutting, a cuttability prediction of the new stone in order to avoid dangerous and expensive cutting endeavors when an unknown stone is being worked upon. In order to predict stone workability, the results of ultrasonic pulse velocity and Knoop micro-hardness on 18 different types of stone was correlated. Seven classes were drawn as follows : from 1 (easier to cut rocks) to 7 (harder to cut rocks). The results of this rock cuttability scientific classification provide a good correlation with the industrial classification.     

R1234yf整车汽车空调泄漏扩散研究

新能源电动汽车热管理系统与传统乘用车不同,对采用热泵空调系统并利用液冷冷却电池的新能源电动汽车,制冷剂充注量比传统汽车空调增加了400～800 g.若使用可燃制冷剂,泄漏扩散至乘员舱,燃烧风险将增大.本文通过数值模拟对R1234yf制冷剂在蒸发器破损泄漏随送风进入乘员舱后的浓度变化过程和最高浓度进行了动态监测.结果表明...     

Strengthening of masonry arches with Textile-Reinforced Mortar: experimental behaviour and analytical approaches

The continuous and growing interest in the conservation of historical heritages requires easy to use and reliable strengthening systems with related calculation methods that allow evaluating the capacity of existing and strengthened masonry structures. However, the analytical models applicable to retrofitted masonry structures have not been developed at the same level as those of other modern construction materials. In particular, there is a gap between the experimental results of masonry elements strengthened with innovative systems and the predicted structural behaviour provided by analytical models. This can hinder exhaustive analysis of experimental results and potentially led to over conservative design methods for innovative strengthening solutions. The present work investigated the performance of the basalt textile reinforced mortar (BTRM) strengthening system, applied to stone masonry arches, and evaluated the applicability of three different analytical approaches for design purposes. The basic materials and the BTRM composite were tested for the definition of the main constitutive laws. Three unreinforced stone masonry arches and nine arches retrofitted according to three different layouts were tested under vertical monotonic load. The experimental and analytical results were compared for the identification of the more suitable analytical approach for design purposes.     

Fracture mechanics analysis of row shear failure in dowelled timber connections: asymmetric case

A quasi-nonlinear fracture mechanics model is presented for analysis of row shear failure in timber connections with multiple fasteners in a row. A prerequisite for use of the model is a known or assumed distribution among the fasteners of the total load applied on the connection. The model is capable of handling an asymmetric case, e.g. an outer row in a connection with multiple rows of fasteners where the edge distance is different from half the row spacing. Pure fracture mode II and usual assumptions used in the Volkersen-model are adopted, leading to simple explicit solutions. Maximum stress as well as mean stress failure criteria are considered. The model is compared with experimental data found in the literature on symmetrical single dowel connections, nearly symmetric multiple dowel connections, and highly asymmetric multiple dowel connections.     

Medical diagnostic system based on simultaneous multispectral fluorescence imaging

A multicolor fluorescence imaging system applied to medical diagnostics is described. The system presented simultaneously records four fluorescence images in different wavelength bands, permitting low-resolution spectroscopy imaging. An arithmetic function image of the four spectral images is constructed by a pixel-to-pixel calculation and is presented on a monitor in false-color coding. A sensitive detector is required for minimizing the excitation energy necessary to obtain an image and thus avoid side effects on the investigated tissue. Characteristics of the system of importance for the detector sensitivity as well as image quality are discussed. A high degree of suppression of ambient background light is reached with this system by the use of a pulsed laser as an excitation source together with gated detection. Examples of fluorescence images from tumors on the hind legs and in the brain of rats injected with Photofrin are given.     

Emission of airborne fibers from mechanically impacted asbestos-cement sheets and concentration of fibrous aerosol in the home environment in Upper Silesia, Poland

The emission rate ((S)) of fibers released from asbestos-cement plates due to mechanical impact was determined experimentally. The emission rate has been defined as a number of fibers (F) emitted from a unit area (m(2)) due to the unit impact energy (J). For fiber longer than 5 microm the obtained surface emission factor for asbestos-cement slabs slightly increased with deteriorating surface, changing from 2.7 x 10(3) F/(m(2)J) for samples with a very good surface to 6.9 x 10(3) F/(m(2)J) for the sample with worn surface (in the SI system the emission rate unit should be (m(-2)J(-1))). The emission rate for short fibers (L < or = 5 microm) was little higher compared with emission of long fibers for all studied asbestos materials. The averaged emission rate for all studied samples was about 5000 and 6000 of long and short fibers, respectively, emitted per square meter (because of the impact energy equal to 1J). The dominating population of emitted fibers ranged from 2 to around 8 microm in length. The second part of this work constitutes the report on the concentration of airborne respirable fibers, and their length distribution in two different groups of homes in Upper Silesia, Poland. Mean concentration level of the respirable fibers, longer than 5 microm, was found to be 850 F/m(3) (according to the SI system the fiber concentration unit is (m(-3))) in the buildings covered with asbestos-cement sheets and 280 F/m(3) in the homes without asbestos-containing facades, located away from other asbestos sources. Although the laboratory and field measurements have been made by using the MIE Laser Fiber Monitor FM-7400 only, the obtained results indicate that the outdoor asbestos-cement building facades are significant sources of airborne fibers inside the dwellings in Upper Silesian towns.     

藏式石砌体受压应力-应变全曲线特征研究

为了研究藏式石砌体轴心受压下的变形特征和损伤机理,对2组共8个三石叠放的棱柱体试件进行了轴心受压试验。2组试件分别反映普通毛石砌筑风格和藏式风格。得到了试件的开裂及破坏形态、变形特征和受压全过程应力-应变曲线。试验结果表明,藏式石砌体具有阶段性变形和损伤特征,应力-应变曲线与其他类型砌体存在差异。根据试验现象和试验数据提出了藏式石砌体轴心受压的开裂前应力-应变曲线本构关系表达式,采用两段式二次多项式来表达。该表达式与实验结果吻合度较好。对试验的适用性进行了探讨,提出了对后续试验的建议。     

Fachgerechte Erstellung von Fugen in Verblendfassaden

Für die Erstellung optisch einwandfreier Verblendfassaden mit sachgerecht ausgeführtem Witterungsschutz bietet die Industrie Werktrockenmörtel an, die an die unterschiedlichen Steinqualitäten angepasst wurden. Gute Argumente für die Baustellenpraxis bieten Vormauermörtel, bei denen die Fugengestaltung mit dem Fugenglattstrich “aus einem Guss” erfolgt. Bei Verwendung von speziellen Fugenmörteln ist auch mit nachträglicher Verfugung eine dichte Fuge zu erzielen. Mörteltechnische Optimierungen, die aus zahlreichen Untersuchungen abgeleitet wurden, können die “Härten der Baustellenpraxis” abmindern. Nach wie vor ist aber die Beachtung ausführungstechnischer Hinweise von höchster Bedeutung. Professional preparation from joints in facades with facing brickwork. For the preparation from optically intact facades with facing brickwork, with a properly functioning weather protection, the mortar industry offers premade dry mortars, which are adapted to the different types of brick qualities. Good arguments for the construction site praxis are achieved by masonry mortars by which the joint design can be done directly in one step. Through the use of special joint mortars you can achieve in a subsequent application a very tight joint. Technical optimizations within the premade mortar products, which have been won on numerous praxis tests, can help to reduce complications on the working site. Nonetheless is extremely important to follow the application notices for a correct application.     

Determination of mycophenolic acid and mycophenolate mofetil by high-performance liquid chromatography using postcolumn derivatization

An efficient method to lower the optical detection limit is described using the displacement of an absorption and emission band of an analyte after a polarity change in different solvents. This solvatochromic effect was used in a RP-HPLC assay for the fluorescence detection of mycophenolic acid (6-(4-hydroxy-6-methoxy-7-methyl-3-oxo-5-phthalanyl)-4-methyl-4-hexenoic acid, MPA) and the prodrug mycophenolate mofetil (MMF), the N-(2-hydroxyethyl)morpholino ester of MPA. The rational to use fluorescence detection is based on the behavior of MMF and MPA, which fluoresce in a basic medium (pH >9.5). Following a simple protein precipitation, the analytes were separated in an isocratic RP-HPLC system. The postcolumn generation of the phenolate anions of MPA and MMF was achieved by addition of an aqueous sodium hydroxide solution regulated by a newly developed continuous-flow liquid control system. MPAG, not directly accessible for fluorescence detection, was analyzed after enzymatic deglucuronidation to MPA. Compared to published quantification limits for MPA and MMF by UV detection, this method is more than 100-fold more sensitive, with a lower limit of quantification of 45 fmol for both MPA and MMF.     

Recent Advances in Perovskite-Based Building-Integrated Photovoltaics

Perovskite-based solar cells have attracted great attention due to their low cost and high photovoltaic (PV) performance. In addition to their success in the PV sector, there has been growing interest in employing perovskites in energy-efficient smart windows and other building technologies owing to their large absorption coefficient and color tunability. The major challenge lies in integrating perovskite materials into windows and building facades and combining them with added functionalities while maintaining their remarkable power conversion efficiencies. Herein, advances that have been made in the application of perovskites to building-integrated photovoltaics (BIPVs) in four areas are highlighted: semitransparent windows, colorful wall facades, electrochromic windows, and thermochromic windows. In addition, the opportunities and challenges of this cutting-edge research area and important roadmaps for the future use of perovskites in BIPVs are discussed.     

In vitro comminution of model renal calculi using histotripsy

Shock wave lithotripsy (SWL) suffers from the fact that it can produce residual stone fragments of significant size (>2 mm). Mechanistically, cavitation has been shown to play an important role in the reduction of such fragments to smaller debris. In this study, we assessed the feasibility of using cavitationally-based pulsed ultrasound therapy (histotripsy) to erode kidney stones. Previous work has shown that histotripsy is capable of mechanically fractionating soft tissue into fine, acellular debris. Here, we investigated the potential for translating this technology to renal calculi through the use of a commonly accepted stone model. Stone models were sonicated using a 1-MHz focused transducer, with 5-cycle pulses delivered at a rate of 1 kHz. Pulses having peak negative pressures ranging from 3 to 21 MPa were tested. Results indicate that histotripsy is capable of effectively eroding the stone model, achieving an average stone erosion rate of 26 mg/min at maximum treatment pressure; substantial stone erosion was only observed in the presence of a dense cavitational bubble cloud. Sequential sieving of residual stone fragments indicated that debris produced by histotripsy was smaller than 100 μm in size, and treatment monitoring showed that both the cavitational bubble cloud and model stone appear as hyperechoic regions on B-mode imaging. These preliminary results indicate that histotripsy shows promise in its use for stone comminution, and an optimized erosion process may provide a potential adjunct to conventional SWL procedures.     

A novel nozzle design for producing hydroentangled nonwoven materials with minimum jet-mark defects

The presence of jet-marks, or jet-streaks, on the surface of hydroentangled nonwoven fabrics, is usually regarded as an undesirable outcome of the hydroentangling process. Jet-streaks degrade aesthetic features and physical properties of the resulting fabrics. Jet-streaks are associated with low tear strength along the machine direction and non-uniform appearance. Reducing or eliminating the occurrence of jet-streaks will lead to increased use of this class of fabrics in many applications. Hydroentangling employs closely-packed single or multiple rows of high-speed waterjets to entangle and consolidate fibers or filaments in a loose (un-bonded) web. In this work, we demonstrated that a waterjet curtain made of two rows of staggered jets where the jets in the 2nd row are smaller in diameter than those in the 1st row can help minimize these jet-marks in a cost-effective manner. The optimal ratio between the diameter of the jets in the 1st and 2nd row depends on the hydroentangling pressure, as well as the web characteristics. In this study, different nozzle diameters ranging from 100 μm to 130 μm for the 2nd row were examined in combination with a fixed diameter of 130 μm for the nozzles in the 1st row. For the type of fiber-web used and the operating pressures considered, a combination of nozzles with 130 μm diameter in the 1st row, and nozzles with 110 μm diameter in the 2nd row, was found to provide the optimum setting for eliminating/minimizing the jet-marks.     

Re‐Use of Marble Stone Powders in Producing Unsaturated Polyester Composites

The main goal of this study is to evaluate the potential of waste stone powders as filler in composite materials with a matrix of unsaturated polyester. These wastes are generated in the form of stone fragments and stone‐cutting sludge. Ground marble wastes are thoroughly characterized with the aim to use them as fillers: Mineralogical and chemical composition, particle size distribution, and morphology of these waste stone powders are investigated. Unsaturated polyester resin composites with the different stone powder fillers are prepared. The influence of powder type on the composites’ mechanical properties (tensile, bending, impact, and hardness characteristics), water resistance, thermal stability as well as surface fracture morphology of composites are studied. The moduli of the composites increase by 100%, the hardness of the composites may be improved by 80% upon loading with the “waste” filler, leading to an economical material and helping to reduce waste.

     

Parametric analysis of runway stone lofting mechanisms

The influence of various factors affecting the severity of runway debris lofting mechanisms was investigated by performing numerical simulations and drop-weight impact experiments to assess the likelihood of a stone impact. Geometrical characterisation of stones collected from airfields led to a generic model of a tyre rolling over stones of various shape with different overlaps, orientations, and densities. In numerical simulations of a 0.4 m diameter aircraft tyre rolling at 70 m/s, a 10 mm diameter spherical stone was lofted at a maximum vertical speed of 35 m/s. For equivalent mass prolate spheroid stones, the loft speeds were 11–34% lower depending on the stone orientation. Objects with flat surfaces exhibited different lofting mechanisms and lower angular velocities. The conditions most conducive to stone lofting were very stiff, small diameter, sharp cornered tyres rolling on ground with a high friction coefficient over spherical stones such that just under half the stone diameter was covered by the tyre. The stone loft speed was approximately proportional to the square root of the tyre tread stiffness. Finally, tyre tread grooves could throw stones upwards at the tyre-ground separation speed, which was 17 m/s for the conditions mentioned earlier.     

粗骨料对沥青混凝土开裂阻力影响分析

沥青混凝土是典型的非均匀材料,在进行力学分析时通常是将其视为均匀、各向同性体,但是理论分析结果很难与实际相符合。同时均质化假设也很难解释含大粒径骨料的沥青碎石作为防裂层的抗裂性能优于小粒径沥青混凝土的现象。笔者通过在均质的沥青混凝土引入一个粗骨料,应用断裂力学平面有限元程序系统地分析了粗骨料对沥青混凝土抗裂性能的影响,分析结果可以较好地解释大粒径沥青混凝土的抗裂性能优于小粒径沥青混凝土的机理。因此,使用大粒径骨料沥青混泥土能够改善路面的使用寿命。