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Mobility of long-runout catastrophic landslides (debris flows, debris and rock avalanches) can be characterized by several parameters. Those, allowing predicting exposure of elements at risk that might be threatened by such hazardous natural phenomena if they will occur—the affected area and runout, are most important for risk assessment. They can be estimated using two general approaches—one based on the numerical modeling and another one based on the empirical relationships between runout and affected area on the one hand and parameters characterizing the potential source zone on the other hand. The latter are volume of the anticipated rock slope failure and height of the unstable slope. Both can be assessed prior to failure with certain accuracy by contrast with the height drop defined as the elevation difference between headscarp crown and the deposit tip. The optimal input parameter is the product of the unstable slope height and possible failure volume that is, in general, proportional to the potential energy of the unstable rock massif. According to the analysis of the Central Asian rockslides/rock avalanches database that includes quantitative parameters of 515 case studies with defined confinement, the relationships of such product with runout and affected area have high correlation coefficients regardless of the confinement conditions and, therefore, allow prediction of the parameters in question with sufficient reliability. It is pointed out that requirements to the accuracy of slope height and failure volume assessment depend on a large extent on the variability range of these parameters within the inventories used to derive the empirical relationships. [ABSTRACT FROM AUTHOR]

This study aims to solve the freezing problem of the 5 mm water layer remaining in the upper water chamber after elf-weight drainage of the tube and fin heat exchanger in the low-temperature wind tunnel under low-temperature operating conditions. Under the conditions that the hot air temperature inside and outside the tube are 10-70 °C and the inlet air speed s 2.78-10.56 m/s, two types of tube (elliptical tube and aluminum flat tube) and fin heat exchangers are tested and studied or drying the water layer remaining in the upper water chamber after self-weight drainage. The influence of the hot air inside and hot air outside the tube drying methods on the drying rate of the two heat exchangers are compared and analyzed. The results show that: the drying rate of aluminum flat tube heat exchanger is faster, so as the hot air outside the tube drying method; the heat exchanger drying time decrease with the increase of the inlet air speed and the drying time saves 50.75% at he inlet air speed of 10.56 m/s compared to 2.78 m/s. The empirical relationship equation for the drying rate was fitted by he experimental data, and the average error between the fitted results and the experimental measurements was less than 6.1%, which has a good prediction capability for the hot air drying rate of the tube-fin heat exchanger in the low-temperature wind tunnel. [ABSTRACT FROM AUTHOR]

Environmental considerations are an important aspect of construction activities, such as the impact of construction vibrations at project sites and in nearby properties. There are limited studies to investigate the impact of vibration from ground improvement construction and how underground utilities can be protected from vibration damage. This research is aimed at developing empirical formulations that can be used to predict ground particle velocities near buried structures. This will allow engineers to minimize potential vibratory damage to buried structures. In this study, ground vibrations are produced by the installation of rockfill columns, a ground improvement technique to stabilize riverbanks. Installation of rockfill columns was done near a buried aqueduct. So, there is a concern that this aqueduct can be damaged by ground vibrations. Finite-element analysis was done to provide information on ground vibrations caused by the installation of rockfill columns. The finite-element models were calibrated with particle velocities measured at the construction site. Results showed that the particle velocities obtained in the numerical models correlated well with the measured particle velocities and those reported in the literature (although from different sources of vibrations). Empirical relationships are proposed between ground vibrations and their impacts on nearby buried structures. Limiting ground vibration on structures near construction sites is a challenging task. Even though most guidelines use peak particle velocity (PPV) as the limiting parameter, there is no consensus as to which limiting values to use. Ideally, project-specific values could be estimated with predicting equations. Estimation of the vibratory impact from the installation of rockfill columns in the ground and their impact on buried structures is limited in the literature. This is due to the lack of data to validate prediction methods. As is shown in this paper, numerical results in this research reasonably agree with field PPVs reported in the literature. Therefore, empirically based predictions for the installation of rockfill columns, for the removal of steel casings, and for the vibratory impact of ground vibrations on buried structures for 5%, 50%, and 95% exceedances are proposed in this study. It is recommended that the proposed empirically based predictors be used as a preliminary evaluation tool, preceding numerical simulations to predict expected ground vibration in terms of PPV. It is understood that when the field data are obtained in the near field but prediction is for far field, the predictions tend to be conservative. On the other hand, prediction for the near-field response based on data from the far field is inappropriate and should be used with caution. In the field, well-planned instrumentation and monitoring would help protect buried structures from potential damage from ground vibrations, which was done in the case study presented in this paper. [ABSTRACT FROM AUTHOR]

The imaging of subsurface soil velocity structures from ambient noise inversion is a difficult problem. Few recording points and a simplified 1-D layered profile lead to important non-uniqueness. From our point of view, improving the reliability of processing methods of the observed data to obtain noise horizontal-to-vertical spectral ratio (NHV) curves and setting a complete model parameter space are important tasks to reduce the non-uniqueness of inversion. In this study, using a local site near the border of the Tonghai Basin, China, as a case study, we first demonstrate how to identify and mitigate the influence of industrial sources using surface observations to obtain more reliable NHV curves. Then, a new strategy to determine model parameter space is proposed, that is, stratifying soil layers based on the number of NHV peaks and determining the shear wave velocities, thicknesses, and their ranges based on the empirical relationship between sedimentary thickness and resonant frequency (h-fr). Subsequently, combining the model parameter space acquisition strategy with the NHV inversion, a novel NHV inversion approach is developed and applied to obtain the 2-D VS profile of the investigated Tonghai site. The inverted 2-D VS profile aligns favorably with the frequency-depth conversion results of the measured NHV curves (NHV-profiling) and the measured borehole profiles, affirming the reliability of the proposed NHV inversion method. Finally, by comparing the empirical transfer functions from the strong-motion recordings, we validated the applicability of the inverted models for characterizing site effects. The model parameter space acquisition strategy proposed in this paper and the analysis procedure of the observed data are also applicable to other study areas, which can provide a referable approach to quickly and effectively acquire the soil layer velocity structure of the site.

Shear logs, also known as shear velocity logs, are used for various types of seismic analysis, such as determining the relationship between amplitude variation with offset (AVO) and interpreting multiple types of seismic data. This log is an important tool for analyzing the properties of rocks and interpreting seismic data to identify potential areas of oil and gas reserves. However, these logs are often not collected due to cost constraints or poor borehole conditions possibly leading to poor data quality, though there are various approaches in practice for estimating shear wave velocity. In this study, a detailed review of the recent advances in the various techniques used to measure shear wave (S-wave) velocity is carried out. These techniques include direct and indirect measurement, determination of empirical relationships between S-wave velocity and other parameters, machine learning, and rock physics models. Therefore, this study creates a collection of employed techniques, enhancing the existing knowledge of this significant topic and offering a progressive approach for practical implementation in the field.

The magnitude (spatial location, area, and volume) of landslides is a crucial parameter for estimating the quantitative risk and preventing landslide hazards. This study proposes a novel approach to forecast the volume of potential landslides in alpine-canyon terrain by combining the empirical relationship linking landslide volume (V) to characteristics and synthetic aperture radar interferometry (InSAR) technology in the northeast of the Qinghai-Tibet Plateau, China. First, a historical landslide inventory with detailed characteristics was established by reviewing literature and field investigation. Then, the relationship between volume and characteristics of landslides was analyzed based on the least-squares linear regression of the logarithmic transformation. Finally, the relationships of the colluvial landslides (V = 0.170 × L 0.982 × W 1.589 × H 0.471) and loess landslides (V = 0.170 × L 0.796 × W 2.151 × H 0.048) were obtained after verifying several landslides. The ground deformation rate was generated, and 217 potential landslides were detected using 47 descending Sentinel-1A images acquired from January 11, 2020, to July 16, 2021, and 40 ascending Sentinel-1A images acquired from January 11, 2020, to April 23, 2021. Through the established relationships, the total volumes of all potential colluvial and loess landslides were estimated to be 8.77 × 108 m3 and 5.74 × 108 m3, respectively. This study provides an improved empirical relationship to better forecast the volume of potential landslides in alpine-canyon terrain. Furthermore, the study helps in understanding the future dynamic evolution of potential landslides using InSAR technology, which provides scientific understanding to assess and prevents potential landslide hazards and risks in the Bailong River basin. [ABSTRACT FROM AUTHOR]

Thermal characteristics such as thermal conductivity and specific volume heat capacity are the significantly important parameters for the backfill materials for underground power cable. Herein, the thermal characteristics of fly ash (fluidizer), bentonite, and their mixes (fly ash content: 20%, 40%, 50%, and 70% by mass) were measured using a KD2 Pro thermal probe, and the effect of fly ash content and volumetric water content were studied. The experimental results indicate that the thermal conductivity and specific volume heat capacity increased with increase in the fly ash content and the volumetric water content. Further, a correlation between thermal conductivity versus volumetric air content and fly ash has been established based on experimental results. The established correlation was verified with the data obtained from the present study as well as from the data available in existing works of the literature. The proposed calculation model estimated the thermal conductivity with relative error of 8.53–16.40% of bentonite and bentonite–fly ash mixture. The predicted result showed that the established correlation will be useful to predict the thermal conductivity of bentonite–fly ash or similar soil and soil mixtures. The experimental outcomes can be widely applicable for thermal backfill applications for underground power cable systems. [ABSTRACT FROM AUTHOR]

The CLP (Chinese Loess Plateau) is one of the most densely distributed landslides areas. The empirical relationships of the landslides in the CLP remain unclear, and its influencing factors are controversial. According to regional landslide data, this paper studies the relationships and discusses the factors affecting landslides in the CLP. The results show that the area (A) -volume (V) of landslides follows a power law trend described by V = 1.53 A1.19 and the frequency distribution range of H/L (height drop (H)/travel length (L)) is between 0.2 and 1.0, more specifically between 0.2 and 0.4, accounting for 26.1% of the total landslides, indicating that the landslides primarily belong to long run-out landslides. The function of V and H/L of the landslides is followed by H/L = 2.39 V−0.102. About 87% of the landslide is distributed within the equilibrium or mature stages of the watershed. The landslide’s size increases, and the slope of the landslides are steeper with an increase in HI (hypsometric integral). Meanwhile, the loess thickness, human activities, and slope effects on landslides induce landslide occurrence and have positive and negative effects on the landslides within the CLP. With climate change, the risk of landslides will increase in the CLP.

Plain carbon steels of five different carbon contents up to eutectoid composition have been provided with the conventional full annealing treatment. Qualitative and quantitative studies of the microstructure are carried out using optical microscopy and field emission scanning electron microscopy techniques. Even under similar cooling rate pertaining to the full annealing treatment (furnace cooling); microstructural modifications of individual microconstituents are feasible with varying chemistry (carbon content) of plain carbon steel. The refinement of microstructure for both proeutectoid α‐ferrite and pearlite is found to be accentuated with increasing carbon content of annealed steels till eutectoid composition. Hall‐Petch type relationship explains adequately the relationship between hardness and the size of the microconstituent both in terms of the grain size of proeutectoid α‐ferrite and the interlamellar spacing of pearlite. Henceforth an empirical relationship is developed for the first time taking into account the rule of mixture to correlate overall hardness, carbon content, grain size of proeutectoid α‐ferrite and interlamellar spacing of pearlite. The empirical relationship originated thereby is found to closely match the experimental results. [ABSTRACT FROM AUTHOR]

The cementation factor is one of the basic parameters for calculating water saturation and then hydrocarbon saturation of reservoirs. The best way to determine the cementation factor is through laboratory measurements. To generalize this coefficient for samples without laboratory measurements, experimental relationships versus petrophysical properties by researchers can be somewhat helpful. The method of artificial neural networks, with the help of training, validation, and data analysis, has given better results in determining the cementation factor of carbonate samples. It is one of the best methods to use petrophysical data as training data and make acceptable predictions with analytical methods. Therefore, laboratory measurement of the cementation factor has been performed for 159 carbonate cores from the Sarvak formation in southwest Iran. For the studied samples, the cementation factor in porosity was determined as a quadratic equation with the highest correlation coefficient. In this study, the compatibility of the experimental relationship shows better conformity by considering the permeability of each sample. Improvement of empirical relationships by the authors, correlation coefficients between the laboratory data, and the experimental relationships have been increased. Therefore, it is better to use improved experimental relationships for the studied carbonate samples. Artificial neural network methods have been used to process the data, best adapt the laboratory data, and present a suitable model. The Bayesian Regularization algorithm with five hidden layers has the least error in the test, validation, and testing stages.

Hydraulic conductivity is a vital hydraulic property of porous media that influences the movement of water and the transport of dissolved contaminants. The present study investigates the influence of key parameters namely, grain size and porosity on the hydraulic conductivity of the borehole soil samples. Further, the applicability of various porosity functions, nine existing empirical relationships, and the developed statistical model was assessed using experimentally measured values. Experimental investigations show that an increase in the grain size and porosity values results in an increase in the value of hydraulic conductivity. Porosity function corresponding to the Kozeny-Carman relationship provides the best fit with the measured hydraulic conductivity. The hydraulic conductivity computed using the Kozeny-Carman relationship indicates close agreement with the measured values followed by Beyer, Hazen, and Alyamani and Sen relationships while other relationships underestimate the hydraulic conductivity of the considered borehole soil samples. The values obtained using the developed model indicate better agreement as compared to those based on the empirical relationships, with the measured values of hydraulic conductivity. The reasonable values of SI, Cc, RMSE, and MAE i.e., 0.012, 0.984, 0.001, and 0.001 respectively, postulate substantial performance of the developed model in computing hydraulic conductivity. [ABSTRACT FROM AUTHOR]

The imaging of subsurface soil velocity structures from ambient noise inversion is a difficult problem. Few recording points and a simplified 1-D layered profile lead to important non-uniqueness. From our point of view, improving the reliability of processing methods of the observed data to obtain noise horizontal-to-vertical spectral ratio (NHV) curves and setting a complete model parameter space are important tasks to reduce the non-uniqueness of inversion. In this study, using a local site near the border of the Tonghai Basin, China, as a case study, we first demonstrate how to identify and mitigate the influence of industrial sources using surface observations to obtain more reliable NHV curves. Then, a new strategy to determine model parameter space is proposed, that is, stratifying soil layers based on the number of NHV peaks and determining the shear wave velocities, thicknesses, and their ranges based on the empirical relationship between sedimentary thickness and resonant frequency ( h - f r ). Subsequently, combining the model parameter space acquisition strategy with the NHV inversion, a novel NHV inversion approach is developed and applied to obtain the 2-D V S profile of the investigated Tonghai site. The inverted 2-D V S profile aligns favorably with the frequency-depth conversion results of the measured NHV curves (NHV-profiling) and the measured borehole profiles, affirming the reliability of the proposed NHV inversion method. Finally, by comparing the empirical transfer functions from the strong-motion recordings, we validated the applicability of the inverted models for characterizing site effects. The model parameter space acquisition strategy proposed in this paper and the analysis procedure of the observed data are also applicable to other study areas, which can provide a referable approach to quickly and effectively acquire the soil layer velocity structure of the site., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Rock mass classification systems are valuable tools for estimating design parameters of rock engineering projects. In some cases, due to the lack of enough geological data, it may not be possible to use a specific classification system. Many researchers have attempted to develop empirical correlations between classifications. However, these relationships are not applicable in all geological conditions and are highly site specific. Hence, it is necessary to introduce different geology-specific empirical relationships. In this paper, geological and engineering geological data from 107 sections of three mechanized tunneling projects, constructed in different geological zones of Iran, were collected, screened, and compiled in a database. To take into account the engineering geological conditions, the collected data were first categorized based on the conditions of rock masses in the tunnels. Two important parameters of lithology and rock mass structure were the basic criteria for categorizing the collected data. Then, the relationships between different classifications including RMR, Q, and GSI in categorized engineering geological conditions were investigated. In addition, for the first time, some empirical relationships between usual rock mass parameters and less-known parameters, which apply in the NTNU model (proposed for predicting TBM performance), were developed to facilitate the application of this model. Statistical analysis of the developed relationships shows that the geological characteristics are very important in development of these relationships. Parameters such as presence of clayey and foliated rocks, thickness of beds, and number of discontinuity sets are some of the factors that affect these relationships. [ABSTRACT FROM AUTHOR]

The preliminary responses on stability assessment are very effective in discontinuous rock slope stabilisations, which geo-mechanical empirical classifications/approaches can be evaluated. Although there are several geomechanical classifications for rock mass characteristics, they still have some complexities and shortcomings. In this paper, correlations based on two flexible classification systems, namely slope mass rating (SMR) and Barton's Qslope, has been discussed as a connection between failure (i.e., safety factor, reliability) and stability conditions (i.e., failure mechanism, support system) which were performed in 300 road/railway slope cases from 12 provinces in Iran. The empirical SMR-Qslope relationship has been used for sedimentary rocks defined lithologically as limestone, marlstone, sandstone, and claystone. The method was used to provide the empirical link to the primary design for discontinuous rock slopes. To this end, after field investigations and the necessary geo-engineering data gathered on the studied slopes. The information used to provide the SMR and Qslope retirements prepare SMR-Qslope relation for Iranian data. The artificial intelligence techniques including k-nearest neighbours, support vector machine, Gaussian process, decision tree, random forest, multilayer perception, and Naïve-Bayes classifiers have been used for detailed classifications. The accurate correlations provided have been implemented and revised in the Python programming language. According to the learning model results, SMR-Qslope equation for Iranian data has been developed as SMR = 6.699 ln (Qslope) + 58.99 / R2 = 0.62 with 0.95 (95%) accuracy. The evaluated results were verified and controlled by Jorda-Bordehore et al. (Stability assessment of rock slopes using empirical approaches: comparison between slope mass rating and Q-slope, 2018) and Maion (Proposta de correlação entre os índices SMR e Q-slope , 2019) empirical relationships as a basic table. By comparing these studies' results, it can be stated that the present study has improved the accuracy of SMR-Qslope relationship. [ABSTRACT FROM AUTHOR]

The quest to implement innovative practices that will lead to a high level of sustainability at the firm level within the construction sector cannot be overemphasised. The aim of this study is to establish the empirical relationship between organisational innovativeness and sustainability of construction firms using a structural equation modelling approach. The study has adopted a survey approach and 1179 copies of structured questionnaire have been administered to construction firm representatives. A total of valid 980 copies of questionnaire have been received giving a response rate of 83.2 %. Data collected have been analysed using descriptive statistics and structural equation modelling. The correlation coefficient (β = 0.81) shows that organisational innovativeness positively influences the sustainability of construction firms. The study reveals that 66.1 % of the variability in the overall sustainability of construction firms operating in the Niger Delta region of Nigeria is accounted for by the implementation of innovative practices by the construction firms. It is concluded that 67.1 %, 83.8 % and 45.7 % of the variability in the construction firm’s social, environmental and economic sustainability, respectively, are explained by the implementation level of innovative practices by the top management teams of the firms. In line with the findings, this study concludes that efficient implementation of innovative practices at the firm level has a significant and positive influence on the overall sustainability of construction firms.

In this research paper, an endeavour was made to devise empirical relations amidst the process parameters of friction stir welding (FSW) and tensile relevant strength of AZ80A Mg alloy joints, based on a 6 parameters—5 levels based central composite design (CCD). Mathematical equations illustrating the impact of process parameters of FSW were formulated based on quadratic regression based analysis to optimize the parameters for attaining superior tensile strength and sensitivity related equations were established from these numerical models. A detailed sensitivity characteristic relevant map for the FSW of AZ80A Mg alloys was established forecasting the fine tuning related prerequisites of the employed FSW parameters. Coefficient of determinant (R ^2 ) announced that 99.062% of the overall variability was described by the formulated model and only lower than 1% of the overall variations was not justified by the model. Predicted R ^2 was also in perfect agreement with the adjusted R ^2 and announced the model’s capability to demonstrate 95.43% of the variability in the generated data. Highest value of tensile relevant strength (80.77% of the parent metal) was exhibited by the AZ80A Mg alloy joint fabricated under optimized parameters. Tensile relevant strength of AZ80A Mg joints was observed to be highly sensitive to traverse speed of the employed tool.

Equivalent single-degree-of-freedom (ESDOF) models are widely used to evaluate the collapse capacity of multistory structures, and their rationality is very important because it greatly affects the accuracy of the evaluation results. Prior studies have indicated that obvious cyclic deterioration (CD) behaviors exist before structural collapse, and such deterioration behaviors are the primary sources of collapse for reinforced concrete (RC) frames subjected to long-duration ground motions. Although several ESDOF models have been developed to represent the global mechanical behaviors during the collapse of RC frames, such models cannot reasonably consider CD behaviors. This paper establishes an ESDOF model capable of considering CD behaviors by utilizing the Ibarra-Krawinkler (I-K) model. The ESDOF model includes a monotonic backbone curve with a negative tangent stiffness and a hysteretic rule to consider CD behaviors based on hysteretic energy dissipation. A simple method utilizing the empirical relationship between the monotonic ductility capacity and hysteretic energy dissipation capacity of RC columns to determine the hysteretic energy dissipation capacity of the ESDOF model is proposed. The CD behaviors are simulated by calculating the hysteretic energy dissipation capacity of the ESDOF model using the empirical relationship, which is obtained by the regression analysis of the existing experimental data of the RC column tests. The proposed ESDOF model is validated by pseudo-static collapse experiments and collapse fragility analyses. The results demonstrate that CD behaviors cannot be ignored when performing the collapse analyses of RC frames and that the proposed ESDOF model can adequately predict the collapse capacity of RC frames. [ABSTRACT FROM AUTHOR]

This paper aims at developing an empirical relation to predict the porosity and micro-hardness, by means of High Velocity Oxy Fuel (HVOF) sprayed WC-10Co-4Cr coatings. For determining the coating performance, process parameters such as flow rate of LPG fuel, flow rate of oxygen, spray distance, flow rate of carrier gas and feed rate of the coating powder play a significant role. Five-factors, five-level central composite rotatable design (CCD) was employed in this analysis to reduce the number of experiments by covering all possible combinations of the process variables. A mathematical model was established to assess the porosity and microhardness of the coatings including HVOF process parameters and the appropriateness of the model was examined using analysis of variance. Using RSM, process parameter optimizations were conducted. The coatings produced using optimized process variables had a minimum porosity level of 0.2 Vol. percentage and a maximum hardness of 1325.26 HVx compared to other coatings. This has been confirmed by the developing response graphs and also by plotting contours. The optimization of HVOF parameters using RSM, as well as the correlation of spray variables with properties of the coating, enables the recognition of the framework of the characteristics to attain the preferred consistency of WC-10Co-4Cr coatings. Analysis of Sensitivity is also performed to determine the most significant process parameter for the HVOF operation. [ABSTRACT FROM AUTHOR]

The present study proposes an empirical technique for the prediction of tentative yield expected from a reservoir propounded at any site in the study area. The proposed methodology was validated in two parts considering India as the case study region. In the first part, seventeen major river catchments of the country were examined to establish an empirical relationship between peak flow rate and average flow rate. The former was calculated using the rational formula while the latter was acquired from the WRIS portal. The generated equation provided the average streamflow value by using only the rainfall data of an aspiring reservoir location. In the second part of the validation, a mathematical model was established for computing the yield from a reservoir. The dependent variables were computed using the streamflow dataset of 212 sites, spread widely, across the country's geography. The results of the present study may prove to be beneficial for the reconnaissance planning of a reservoir. The proposed methodology may also be applied to other countries/regions to achieve similar results. [ABSTRACT FROM AUTHOR]

This study is aimed to investigate compressive strength, flexural strength and shear strength of engineered cementitious composites (ECC) with high volume fly ash by replacing cement with Class F fly ash in the range of 40%, 60%, 80%, and 100% respectively. The experimental results shows that compressive strength and flexural strength decreased at 28 days as the percentage of high volume fly ash increased, but when the curing was increased to 90 days, 40% and 60% high volume fly ash engineered cementitious composite exhibited lesser but similar compressive and flexural strength compared to ECC without fly ash. The shear strength decreased as the percentage of high volume fly ash increased in ECC at 28 days. However, the rate of reduction of shear strength decreased when the curing was increased to 90 days. Based on the experimental results, an empirical relationship (exponential) is proposed between shear strength, compressive strength and flexural strength to predict shear strength from compressive and flexural strength at 28 and 90 days respectively. The percentage difference between the experimental and predicted shear strength from the empirical relationship was observed to be lesser than 14% for both 28 and 90 days, thus exhibiting the degree of accuracy for the proposed relationship.

Abstract Frequency‐dependent anelastic attenuation is a fact that must be considered when inverting seismic data. The shallow attenuation characteristics of large sedimentary basins with frequent earthquakes in mainland China are still unclear, which hinders the study of strong ground motion. Borehole seismometers distributed in these areas provide information on shallow structures. In this study, the direct and surface‐reflected phases in local earthquake borehole seismograms were extracted to calculate the average S wave anelastic attenuation of shallow sediments in mainland China. Relying on the seismograms recorded by 103 borehole stations, the attenuation values and lithologies of the shallow sediments above the borehole seismometers were estimated by applying a multi‐time window analysis method. We suggested that the QS−1 values generally decrease from 0.04–0.50 at 1 Hz to 0.01–0.05 at 10 Hz. We obtained the empirical relationships among attenuation, velocity, and depth and found that the dominant mechanisms for attenuation above and below a depth of 400 m could be different due to sediment compositions and scales. Certain borehole depths and corresponding Vs values were corrected by analyzing the time difference variation and the QS−1 distinction.

Frequency‐dependent anelastic attenuation is a fact that must be considered when inverting seismic data. The shallow attenuation characteristics of large sedimentary basins with frequent earthquakes in mainland China are still unclear, which hinders the study of strong ground motion. Borehole seismometers distributed in these areas provide information on shallow structures. In this study, the direct and surface‐reflected phases in local earthquake borehole seismograms were extracted to calculate the average S wave anelastic attenuation of shallow sediments in mainland China. Relying on the seismograms recorded by 103 borehole stations, the attenuation values and lithologies of the shallow sediments above the borehole seismometers were estimated by applying a multi‐time window analysis method. We suggested that the QS−1 values generally decrease from 0.04–0.50 at 1 Hz to 0.01–0.05 at 10 Hz. We obtained the empirical relationships among attenuation, velocity, and depth and found that the dominant mechanisms for attenuation above and below a depth of 400 m could be different due to sediment compositions and scales. Certain borehole depths and corresponding Vs values were corrected by analyzing the time difference variation and the QS−1 distinction. Plain Language Summary: The energy of seismic waves propagating through a medium will dissipate due to internal friction and non‐uniform scattering along the propagation path. Attenuation is an important feature of Earth's media. Strong attenuation has a significant influence on predictions of strong ground motion, especially for sedimentary basins. Moreover, compared to velocity, attenuation is more sensitive to changes in rock properties caused by stress. Therefore, it is important to understand the attenuation of shallow sediments in mainland China, which has high seismicity. More than 100 borehole stations have been established through the development of a seismic network in China. Relying on the seismograms recorded by these underground stations, the attenuation and velocity values and lithologies of the shallow sediments above the borehole seismometers were estimated by applying a robust and reliable analysis method. We also obtained the empirical relationships among attenuation, velocity, and depth. These results can be most useful in the prediction of strong ground motion. The method adopted in this study will also be useful for the evaluation of anelastic attenuation in other sedimentary basins. Key Points: The average QS−1 and VS values of shallow sediments across mainland China are obtainedThe empirical relationships among attenuation, velocity, and depth are obtainedCertain seismometer installation depths and corresponding VS values are corrected [ABSTRACT FROM AUTHOR]

The results of experimental research of heat exchange under the nucleate boiling of refrigerants R404a, R407c and R410a on the tubes with capillary-porous coating are presented. Experimental studies were carried out with the aid of an experimental installation in conditions of a large volume at pressures of saturation pн = 0.9–1.4 MPa and densities of the heat flux q = 5–35 kW/m2. For the first time the criterion equation for the calculation of the intensity of heat transfer during evaporation of ozone safe refrigerants on surfaces with high thermal conductivity sintered capillary-porous coating was obtained. Experimental data are summarized satisfactorily in a wide range of parameters of the porous layer, i.e. the pressure (pн = 0.9–1.4 MPa) and heat loads (q = 5–35 kW/m2). The ratio makes us possible to calculate the heat transfer coefficients within ±20 %. The dependence can be used in engineering calculations of the characteristics of the heat exchangers of the evaporative type. The coefficient of heat transfer during boiling of refrigerants on the investigated surfaces with the sintered capillary-porous coating, 4 times higher than on a smooth one and 1.5 times higher than on the finned surface, that allows us to come to a conclusion about the advantage of porous coatings. Boiling in capillary-porous coating leads to a decrease in weight and size of the installations due to the heat exchange intensification and the size of the tubes smaller as compared to the size of the finned ones.

Seismic bedrock depth represents one of the crucial steps in site response analysis as the input seismic ground motion is propagated from the bedrock level through soil profile column to estimate surface ground motion. In the last two decades, several studies estimated bedrock depth using microtremor horizontal-to-vertical-spectral ratio fundamental (resonance) frequency and known (mostly boreholes) bedrock depth in different regions through power-law regression. In this study, seismic bedrock (H800—depth of the bedrock formation identified by shear wave velocity VS ≥ 800 m/s) is estimated using H/V forward modelling routine in which shear wave velocity profile from geophysical measurements was used as an initial soil model. Based on geological, geophysical and microtremor data, empirical relationships between average shear wave velocity in top 30 m, resonance frequency and bedrock depth are derived. Given evaluation of sedimentary thicknesses showed to be within the range of published studies for similar geological and site characteristics if the errors between different methods, approaches and site parameters are considered. The main limitation to validate proposed relationships is the lack of realistic deep borehole data like in similar studies. Further work is required that should include deep data from borehole drilling, seismic refraction and reflection or vertical electrical sounding. The intention is that presented regressions between resonance frequency, bedrock depth and VS30 would be implemented into nonlinear site amplification model and further development towards Ground Motion Prediction Equations for Croatia. [ABSTRACT FROM AUTHOR]

Glacial lakes are most often located in remote places making it difficult to carry out detailed bathymetric surveys. Consequently, lake depths and volumes for unmeasured lakes are often estimated using empirical relationships developed mainly from small bathymetric datasets. In this study, we use the bathymetry dataset of the Cordillera Blanca, Peru comprising 121 detailed lake bathymetries, the most extensive dataset in the world. We assess the performance of the most commonly applied empirical relationships for lake mean depth and volume estimation, but also investigate relationships between different geometric lake variables. We find that lake volume estimation performs better when derived from lake mean depth, which in turn is estimated from lake width. The findings also reveal the extreme variability of lake geometry, which depends on glacio‐geomorphological processes that empirical–statistical relationships cannot adequately represent. Such relationships involve characteristic uncertainty ranges of roughly ±50%. We also estimate potential peak discharges of outburst floods from these lakes by applying empirical relationships from the literature, which results in discharges varying by up to one‐order of magnitude. Finally, the results are applied to the 860 lakes without bathymetric measurements from the inventory dataset of the Cordillera Blanca to estimate lake mean depth, volume and possible peak discharge for all unmeasured lakes. Estimations show that ca. 70% (610) of the lakes have a mean depth lower than 10 m and very few longer than 40 m. Lake volume of unmeasured lakes represent ca. 32% (5.18 × 108 m3) of the total lake volume (1.15 × 109 m3) in the Cordillera Blanca. Approximately, 50% of the lakes have potential peak discharges > 1000 m3/s in case of lake outburst floods, implying a need for additional studies for risk assessment. © 2020 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Empirical assessments of the influence of invasive species on native species are infrequent because the required long-term data are rarely available. The invasion of silver carp in the Upper Mississippi River System (UMRS) provides a unique opportunity to assess the influence of this invasive species on native fishes because a highly standardized, long-term monitoring program has been sampling the fish communities in six reaches of the UMRS for over 20 years. We analyzed fish abundance (catch per unit effort from electrofishing) and water-quality data collected from 1994 to 2013 from three reaches where silver carp populations have been established since 2000, and three reaches where they are not established. Our results provide empirical evidence of a negative effect of invasive silver carp on native sport fish in the UMRS. Although water temperature, suspended solid concentration, and flooding also differed substantially between control and invaded reaches, only silver carp abundance had a direct negative relationship with the abundance of adult sport fish. Our analyses suggest that the mechanism for this decline may be competition for zooplankton between silver carp and larval/juvenile sport fish. In reaches where silver carp is established, recruitment of juvenile sport fish appears to be constrained relative to reaches where silver carp is not established. [ABSTRACT FROM AUTHOR]

Accurate determination of the overburden pressure obtained by integrating the formation bulk density from surface to the depth of interest is very critical to pore pressure prediction. When information about the formation bulk density is not available, the current practice is to estimate formation bulk density from compressional-wave velocity using empirical relationships. There is no single formation bulk density prediction model that considers lithologic variation in siliciclastic settings. This imposes severe limitations on the application of the existing empirical relationships to any lithological column that consists of several stratigraphic units. In this paper, attempt is made to develop the new formation bulk density prediction models that can be applied to a wide range of lithologies in siliciclastic environments. The new models are validated using wireline log data acquired from two wells in the tertiary deltaic system of the Niger Delta basin. In the new models, formation bulk density is expressed as a function of compressional-wave velocity and shale volume factor. The accuracy of the new models is quantified using statistical analysis. In general, a good agreement exists between the predicted and measured formation bulk density using the newly proposed models. When compared to the existing models, the new models clearly outperform the most widely used empirical relationships. The new models produce the least root-mean-square errors, normal error distributions and least residual values. Unlike any of the existing empirical relationships, the newly developed models can be applied to clean sands, shaly sands and shales with good accuracy. • The new bulk density prediction models for siliciclastic rocks are being proposed. • The new models contain additional shale volume factor. • The new model is tested and validated using actual field data. • The new models outperform the widely used existing empirical models. [ABSTRACT FROM AUTHOR]

• Chloride ions in exposure solution significantly affected formation of compounds in concrete as indicated by XRD results. • OPC exhibited 4.82 and 2.02 times higher apparent chloride diffusion coefficient than PPC and OPC plus fly ash. • PPC exhibited better performance against corrosion as compared to OPC plus fly ash followed by OPC. • Developed empirical relations for OPC and PPC predicted the I corr with higher degree of accuracy for OPC plus fly ash. • Developed empirical relation between E 0 and I corr predicted well the I corr values reported in literature. This study aims to investigate and correlate durability parameters in concrete exposed to external chloride. Tests for corrosion, chloride diffusion, and X ray diffraction (XRD) analysis were performed. Based on results, ordinary Portland cement (OPC) exhibited 4.82 and 2.02 times higher apparent chloride diffusion coefficient than Portland pozzolana cement (PPC) and OPC plus fly ash. Reinforced concrete specimens made with PPC showed better performance against corrosion as compared to those made with OPC plus fly ash followed by OPC. Concentration of chloride ions in exposure solution significantly affected microstructure of concrete as indicated by formation of compounds from XRD results. Developed empirical relationships between durability parameters for OPC and PPC predicted well the corrosion current density for OPC plus fly ash that was independent of model development. [ABSTRACT FROM AUTHOR]

Abstract Experimental research on the behaviour of conventional construction materials subject to extreme loading condition of post-impact-fire has indicated the effect of rate dependent loading history on the temperature performance of these materials. In order to analyse and design structures to withstand such combined loading, it is desirable to develop models that can reflect the mechanical properties of materials under initial impulsive loading and subsequent elevated temperature. In this study, a rate-pre-damage-temperature dependent empirical expression is proposed to predict the residual strength of partially damaged steel-concrete and fibre rein-forced polymer-concrete composite materials, in the form of concrete-filled steel tubes (CFST) and Concrete filled carbon-fibre reinforced polymer tubes (CFFT), at high temperatures up to 600 °C. The developed model is calibrated and validated on the basis of actual experimental data published by the authors. The proposed expression proves to be capable of successfully reproducing material strengths by considering the extent of high strain rate induced pre-damage together with temperature exposure. Highlights • Post-fire low-velocity impact behaviour of CFSTs and CFFTs is investigated. • A rate-pre-damage-temperature dependent expression is proposed. • Model is calibrated and validated against experimental data published by the authors. • Proposed expression proves capable of reproducing residual strengths of materials. [ABSTRACT FROM AUTHOR]

Abstract This study analyzed landslide characteristics under extreme precipitation with regard to present and future scenarios, in order to analyze the effects of climate change on landslide activities. For our study area, we selected two adjacent catchments in northern Taiwan: the Shihmen Reservoir catchment, an area with high-relief topography that is susceptible to landslides at present, and the Xindian River catchment, an area with gentle topography that is not prone to landslides at present. This study established empirical relationships between landslide-area characteristics and rainfall conditions according to rainfall-induced landslides during past typhoon events. The relationships were applied to estimate landslide-area characteristics caused by typhoon events for the base period (1979–2003) and the end of the 21st century (2075–2099) according to the climate change scenario of representative concentration pathways 8.5 (RCP8.5) and dynamical downscaling of rainfall data in Taiwan. We also analyzed rainfall amounts at different recurrence intervals from different rainfall durations for the two catchments. We found that the area with high-relief topography (the Shihmen Reservoir catchment) is relatively prone to landslides currently and that the cumulative rainfall is a key factor controlling landslide-area characteristics. On the other hand, the area with gentle topography (the Xindian River catchment) is less prone to landslides at present, and the rainfall intensity is a key factor controlling landslide-area characteristics. Under the effects of climate change in the near future, both landslide severity and landslide frequency will increase more in areas with gentle topography than in areas with high-relief topography, in response to the more frequent occurrence of a strong typhoon with higher rainfall intensity. Highlights • Different rainfall factors are important for landslides in different areas. • Cumulative rainfall controls landslides in an area with high-relief topography. • Rainfall intensity controls landslides in an area with gentle topography. • Under climate change, landslide severity increases more in a gentle topography area. [ABSTRACT FROM AUTHOR]

In this article, parametric study of single confined fragment launch device was carried out. The configuration proposed was further studied to derive the empirical relationship for effect of fragment size, charge size, confinement thickness on fragment velocity. The simulations were carried out using ANSYSAUTODYNE explicit solver. Fragment velocities were estimated as a function of different parametric combinations of explosive quantities, charge length to diameter ratio, fragment height to diameter ratio, confinement thickness, fragment material and fragment mass. The data was further converted to charge to metal ratio under fragment and confinement. It was observed that, increase in confinement thickness, charge quantity and decrease in fragment height increases the fragment velocity. It is also noted that, charge to metal mass ratio under fragment significantly affects the fragment velocity. At the end, an empirical relationship for fragment velocity interms of all these parameters was established. Using these relations, two velocities 1831.92 m/s and 2523.9 m/s required for NATO STANAG 4496 IM test were estimated. The design parameters for these velocities are presented. Also, the results estimated using the empirical relationship has been compared with published experimental data. Error in the predicted velocities is within the acceptable range. The empirical relationship proposed will be useful for finalization of design of the fragment launch device. [ABSTRACT FROM AUTHOR]

Clouds are a common barrier of satellite optical images and adversely affect applications of remotely sensed optical data sets. The optical thickness of clouds varies spatiotemporally. The thickness can be very thin making the detection of thin clouds difficult. A new cirrus band (Band-9) of Landsat-8 has been added to detect thin clouds. However, the majority of spaceborne optical sensors existed previously or in operation do not have the cirrus band. An algorithm is developed to detect thin clouds without using a cirrus band. In particular, the top-of-atmosphere reflectance of thin clouds is modeled using the empirical relationships of the deep blue and blue bands of Landsat-8 Operational Land Imager. A Landsat-8 image of path 14/row 36 near southeastern North Carolina, USA, is used to validate the algorithm. Thin clouds are well-identified when compared to Landsat-8 Band-9 data. The spatial correlation coefficient for both is 93.49%. Therefore, the algorithm is valid. The algorithm is further verified when a blue band and a green band are used to develop the algorithm. Thus, the analytical approach should be extendible to Landsats 4, 5, and 7 sensors or optical sensors as long as they have a blue band and a green band. Finally, the applicability of the algorithm under various atmospheric conditions is verified after analyzing two water vapor absorption spectral bands of NASA/JPL Airborne Visible/Infrared Imaging Spectrometer data. [ABSTRACT FROM AUTHOR]

Satellite observations revealed that there is a close relationship between perturbations of sea surface temperature (SST) and wind stress (τ) induced by tropical instability waves (TIWs; SSTTIW and τ TIW). Using the empirical relationship observed between TIW-induced wind stress divergence (curl) and downwind (crosswind) SST gradients, this study establishes a TIW-induced wind stress field perturbation model τ TIW = F(SST). This empirical model solves τ TIW from the TIW-induced wind stress divergence and curl, which are estimated from the downwind and crosswind SST gradients. This empirical τ TIW = F(SST) model can be incorporated into the ocean model to take into account the effect of τ TIW. By comparing two experiments with and without the τ TIW effect, this study demonstrates that τ TIW has a substantial effect on the equatorial Pacific heat budget and induces the long-term mean SST to exhibit a 0.2°C difference, which is consistent with previous studies. [ABSTRACT FROM AUTHOR]

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Affected by climate change owing to global warming, the frequency of extreme rainfall events has gradually increased in recent years. Many studies have analyzed the impacts of climate change in various fields. However, uncertainty about the scenarios they used is still an important issue. This study used two and four multi-scenarios at the base period (1979−2003) and the end of the 21st century (2075−2099) to collect the top-ranking typhoons and analyze the rainfall conditions of these typhoons in two catchments in northern Taiwan. The landslide-area characteristics caused by these typhoons were estimated using empirical relationships, with rainfall conditions established by a previous study. In addition to counting landslide-area characteristics caused by the typhoons of each single scenario, we also used the ensemble method to combine all scenarios to calculate landslide-area characteristic statistics. Comparing the statistical results of each single scenario and the ensembles, we found that the ensemble method minimized the uncertainty and identified the possible most severe case from the simulation. We further separated typhoons into the top 5%, 5%−10%, and 10%−15% to confirm possible changes in landslide-area characteristics under climate change. We noticed that the uncertainty of the base period and the end of the 21st century almost overlapped if only a single scenario was used. In contrast, the ensemble approach successfully distinguished the differences in both the average values of landslide-area characteristics and the 95% confidence intervals. The ensemble results indicated that the landslide magnitude triggered by medium- and high-level typhoons (top 5%−15%) will increase by 24%−29% and 125%−200% under climate change in the Shihmen Reservoir catchment and the Xindian River catchment, respectively, while landslides triggered by extreme-level typhoons (top 5%) will increase by 8% and 77%, respectively. Still, the uncertainty of landslide-area characteristics caused by extreme typhoon events is slightly high, indicating that we need to include more possible scenarios in future work.