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Pingtung coastal plain, located at the active convergent boundary between Philippine Sea Plate and Eurasian Plate, is one of the most active areas regarding tectonic deformation in Taiwan. Groundwater over-pumping for aquaculture along the coast area of Pingtung plain induced a serious land subsidence problem for decades. How much land subsidence contributed by tectonic activity and groundwater pumping is a crucial issue for tectonic study and groundwater management in this area. This study collected the data in different fields and proposed a conceptual model to calculate the quantities of land subsidence caused by natural (tectonic) and human (pumping) factors. The data from the Global Positioning System (GPS) are used to illustrate the total subsidence concerning vertical displacement. A system called the multi-level compaction monitoring well (MCMW) is able to measure the vertical compaction in different depths from the earth surface to the depth of 200 m. Two GPS stations, named CLON and FALI, close to two MCMWs, named Jiadong and Fangliao, are adopted for analysis The data during 2007 and 2016 taken from MCMWs and groundwater observation wells indicate that the compaction in the shallow depth should be mainly caused by groundwater over-pumping due to their high correlation coefficients (from 0.58–0.95). The difference of the vertical deformation between GPS and MCMW indicates that there is deformation beyond the depth within 200 m. From the data and literature, the further vertical deformation should be due to tectonic activity associated with tectonic escape and extrusion of the Taiwan orogen with average vertical deformation from −3.0 to −4.4 mm. Therefore, the quantities of land subsidence contributed by local groundwater over-pumping and regional tectonic activities are successfully separated. The method and concept proposed in this study can be used in land subsidence quantification due to both tectonic activity and groundwater over-pumping.

Climate change can directly or indirectly influence groundwater resources. The mechanisms of this influence are complex and not easily quantified. Understanding the effect of climate change on groundwater systems can help governments adopt suitable strategies for water resources. The baseflow concept can be used to relate climate conditions to groundwater systems for assessing the climate change impact on groundwater resources. This study applies the stable baseflow concept to the estimation of the groundwater recharge in ten groundwater regions in Taiwan, under historical and climate scenario conditions. The recharge rates at the main river gauge stations in the groundwater regions were assessed using historical data. Regression equations between rainfall and groundwater recharge quantities were developed for the ten groundwater regions. The assessment results can be used for recharge evaluation in Taiwan. The climate change estimation results show that climate change would increase groundwater recharge by 32.6% or decrease it by 28.9% on average under the climate scenarios, with respect to the baseline quantity in Taiwan. The impact of climate change on groundwater systems may be positive. This study proposes a method for assessing the impact of climate change on groundwater systems. The assessment results provide important information for strategy development in groundwater resources management.

Hydrological anomalies induced by the earthquakes are valuable research data to understand the hydrogeology structure. At the same time, a complete hydrogeological data is the key to the study of earthquake hydrology. In this research, we collected the anomalous hydrological data after the Mw 6.4 2016 Meinong Earthquake in Taiwan. The main purpose is to know the mechanism of hydrological changes triggered by earthquake and understand the local hydrogeological characteristics in the southern Taiwan.From the distribution of the groundwater level change in the same location but different depths of aquifer, as well as the location of the rupture and liquefaction, it could be found that the co-seismic groundwater level change is large in Chianan Plain in the northwest of the epicenter and accompanied with a lot of ruptures and liquefactions located along the Hsinhua Fault. However, the observations in several wells around the Hsinhua Fault show a different water level change pattern compared with the other wells in Chianan Plain. Actually, these wells show that the co-seismic groundwater level decreases in the deep aquifer and increase in the shallow aquifer. It is shown that the Meinong Earthquake may enhance the connectivity between different aquifers near the fault zone and produce an increased vertical pressure gradient. The anomalous hydrological phenomenon also reflected in the river flow. Based on the river flow data we collected from five stations in the Zengwun River watershed, the river flow at two stations in the upstream dose not change after earthquake. There is a little increase at the midstream station. However, a large river flow increase is observed at the downstream station. After excluding the influence of rainfall, we think that the large amount of anomalous flow is caused by the rise of the co-seismic groundwater level between the middle and downstream sections, and a large amount of liquefaction in this area can prove this hypothesis.The hypothesis of connectivity changes between different aquifers can be verified by analyzing the tidal response of different aquifers. Many studies have used the tide analysis to obtain the aquifer permeability and compressibility, and compared the changes in the analysis results before and after the earthquake. We think that if different aquifers are vertically connected after earthquake, the tidal analysis results should show a consistent permeability. Tidal analysis is executing now and the results will be provided at conference.

The fundamental study of coupled thermal–hydraulic-mechanical (THM) systems is an important issue in multi-physical fields. This study developed a THM model in which the hydraulic and mechanical effects are fully coupled and the temperature change serves as the perturbation source of the system. A porothermoelasticity model was applied to investigate the cross-interactions among the temperature, change in pore water pressure, and displacement of a buffer material in the near-field and a host rock in the far-field with the conceptual model in a nuclear waste repository. The results show that the size scale of the domain of interest and the THM properties play important roles in the coupled THM system. The changes in pore water pressure depended on the combined effect of the deformation of the porous space and pore water controlled by the thermal expansion coefficients of the solids and fluids. Stochastic analyses show that the uncertainties of variables varied spatio-temporally due to the thermal influences and approached zero due to the presence of a stable condition. The cross-interactions between displacement and change in pore water pressure induced by the thermal effect were complex and can be determined from statistical moment analyses.

The hydraulic properties of aquitards are not easily obtained because monitoring wells are usually installed in aquifers for groundwater resources management. Earthquake-induced crust stress (strain) triggers groundwater level variations over a short period of time in a large area. These groundwater anomalies can be used to investigate aquifer systems. This study uses a poroelastic model to fit the postseismic variations of groundwater level triggered by the Chi-Chi earthquake to evaluate the hydraulic properties of aquitards in the Jhoushuei River alluvial fan (JRAF), Taiwan. Six of the adopted eight wells with depths of 70 to 130 m showed good agreement with the recovery theory. The mean hydraulic conductivities (K) of the aquifers for the eight wells are 1.62 × 10-4 to 9.06 × 10-4 m/s, and the thicknesses are 18.8 to 46.1 m. The thicknesses of the aquitards are 11.3 to 42.0 m. Under the isotropic assumption for K, the estimated values of K for the aquitards are 3.0 × 10-8 to 2.1 × 10-6 m/s, corresponding to a silty medium. The results match the values obtained for the geological material of the drilling core and those reported in previous studies. The estimated values were combined with those given in previous studies to determine the distribution of K in the first two aquitards in the JRAF. The distribution patterns of the aquitards reflect the sedimentary environments and fit the geological material. The proposed technique can be used to evaluate the K value of aquitards using inverse methods. The inversion results can be used in hydrogeological analyses, contaminant modeling, and subsidence evaluation.

Combating the intersymbol interference is an important issue in single-carrier block transmission systems. To exploit the advantages of frequency-domain (FD) processing, we propose in this paper a hybrid-domain sequence detector that combines FD prefiltering with time-domain tree search detection. The proposed algorithm achieves a detection performance that is very close to that of the conventional tree search equalizers (which employ the QRD-M or sphere decoding algorithm), but with a much lower complexity. In addition, the proposed algorithm performs significantly better than the decision-feedback equalizer, with only a modest increase in complexity.

Groundwater level variations associated with earthquake events may reveal useful information. This study estimates the extent of stress influence, defined as the distance over which an earthquake can induce a step change of the groundwater level, using earthquake-triggering groundwater level variations in Taiwan. Groundwater variations were first characterized based on the dynamics of groundwater level changes dominantly triggered by earthquakes. The step-change data in co-seismic groundwater level variations were used to analyze the extent of stress influence for earthquakes. From the data analysis, the maximum extent of stress influence is 250 km around Taiwan. A two-dimensional approach was adopted to develop two models for estimating the maximum extent of stress influence for earthquakes. From the developed models, the extent of stress influence is proportional to the earthquake magnitude and inversely proportional to the groundwater level change. The model equations can be used to calculate the influence radius of stress from an earthquake by using the observed change of groundwater level and the earthquake magnitude. The models were applied to estimate the area of anomalous stress, defined as the possible areas where the strain energy is accumulated, using the cross areas method. The results show that the estimated area of anomalous stress is close to the epicenter. Complex geological structures and material heterogeneity and anisotropy may explain this disagreement. More data collection and model refinements can improve the proposed model. This study shows the potential of using groundwater level variations for capturing seismic information. The proposed concept of extent of stress influence can be used to estimate the earthquake effect in hydraulic engineering, mining engineering, and carbon dioxide sequestration, etc. This study provides a concept for estimating the possible areas of anomalous stress for a forthcoming earthquake.

Tainan, located in southwestern Taiwan, is a high-risk region for flooding and climate change effect and has a potential for future heavy rains. Groundwater pumping for aquaculture and irrigation along the coastal plain of Tainan is monitored due to subsidence. Predicting future subsidence and understanding the effect of climate change on subsidence can assist with regard to the planning and management of water and land resources in the early stages of subsidence, whose possible damage can thus be avoided. This study combines a physical model, called the nonlinear poroelastic model, and a gray-box model, called the gray system model, to evaluate and predict subsidence in the Tainan area. The subsidence under the climate change effect caused by changes in groundwater use is estimated. The climate change impact on subsidence and the potential for subsidence hazards are also analyzed. When taking into consideration the climate change effect, it is predicted that subsidence in Tainan will increase with increasing groundwater use. The maximum subsidence will increase from 29 cm (without additional discharge) to 34 cm (with additional 23.6 % discharge) and 35 cm (with additional 31.7 % discharge) in Xiaying District by 2039. The pattern of subsidence areas obtained by combining the nonlinear poroelastic and the gray system models is similar to that obtained using only the gray system model. However, the largest subsidence areas are different, and the subsidence quantity is much lower for the former due to the constraint of the physics-based poroelastic model. The combination of the nonlinear poroelastic model and the gray system model gives more reasonable estimations than either model can give alone. Large subsidence impact areas are located in the northwestern part of Tainan, and the largest impact is in Xiaying District. The potential for subsidence hazards is classified from the subsidence rates. The subsidence rate in Tainan is below 3 cm/year in the target years, and thus the potential for subsidence hazards is at middle and low levels. With climate change, the area with a middle level of potential for subsidence hazards extends across Yanshui, Xiaying, and Beimen Districts. From the study results, although the subsidence quantity is relatively low, rising sea levels and other effects of climate change expose Tainan to a high risk of flooding. Land and water resources should thus be managed to alleviate subsidence problems in the future.

Subsidence in Yunlin County, Taiwan, is serious and continuous. The Taiwan High Speed Rail (THSR) route crosses the subsidence area and might be affected by differential settlements. It is important to evaluate the pumping quantity for water resource management and to predict the subsidence for land resource management to mitigate the subsidence problem in Taiwan. This study combines first-order second-moment (FOSM) stochastic poroelastic theory with nonlinear parameters to develop a FOSM nonlinear stochastic poroelastic model and applies it to quantify groundwater pumping and future subsidence with uncertainty. The additional loading and discharge are evaluated by fitting the subsidence historical data to the numerical model. The results show that the proposed model well describes the subsidence behavior and quantifies groundwater pumping. However, the numerical results are larger than the monitoring data at various depths, which might be due to the different compaction situations in individual formations of the aquifer system. The predicted subsidence at the Yuanchang monitoring well is the largest (0.32 ± 0.52 m in 2020) with consideration of the climate change effects, achieved by adding an additional discharge of 31.7 %. The large uncertainty is caused by the large variation of hydraulic conductivity caused by the heterogeneity of the aquifer system, which could be improved by doing more experiments or using a conditioned model. The information provided in this study is useful for the safety of THSR and for land and groundwater resource management in Yunlin County, Taiwan.

The hydraulic properties of aquitards are not easily obtained because monitoring wells are usually installed in aquifers for groundwater resources management. Earthquake-induced crust stress (strain) triggers groundwater level variations over a short period of time in a large area. These groundwater anomalies can be used to investigate aquifer systems. This study uses a poroelastic model to fit the postseismic variations of groundwater level triggered by the Chi-Chi earthquake to evaluate the hydraulic properties of aquitards in the Jhoushuei River alluvial fan (JRAF), Taiwan. Six of the adopted eight wells with depths of 70 to 130 m showed good agreement with the recovery theory. The mean hydraulic conductivities (K) of the aquifers for the eight wells are 1.62 × 10

Summary The interaction of groundwater flow and soil deformation within porous media is a complicated process. Water movement or stress change in porous media result in both deformation and alteration in pore water pressure. In this study, the dynamic interactions of flow and deformation in randomly heterogeneous porous media are analyzed using the stochastic first-order second-moment (FOSM) method. Various flow boundaries are considered, including sudden starts and sudden stops of discharge and recharge. The stochastic model is first verified with the results from Monte Carlo simulations with a constant discharge. The patterns of mean, variance, and covariance solutions obtained using the FOSM method are the same as those obtained using Monte Carlo simulations. The results show that the mean behaviors of water pressure variation and deformation are well explained by the concept of effective stress. The second-moment solutions show monotonic increases in the variances of displacement and changes in pore water pressure with distance away from the prescribed boundary. The cross-covariance of log hydraulic conductivity and change in pore water pressure is initially negative and then becomes positive, whereas that of change in pore water pressure and displacement is initially positive and then becomes negative soon after discharge starts at the boundary. The initial behavior is opposite to that in the later period. This reversal of cross-covariance is attributed initially to stress and later to water flow, and it extends from the boundary and then diminishes quickly with time. The Rhade effect occurs for the mean change in pore water pressure in areas away from the discharge boundary when discharge suddenly stops. The reversal of cross-covariance is also found at various depths immediately after the stop of flow at the boundary for both discharge and recharge conditions due to the dynamic interactions of flow and deformation. The results also show that the strength of the dynamic interactions between groundwater flow and soil stress increases with decreasing mean hydraulic conductivity and average stiffness of randomly heterogeneous porous media. Neglecting the dynamic interactions of flow and deformation leads to misinterpretation of aquifer properties and increases estimation uncertainty.

A physics-based method is proposed for simultaneously obtaining the hydraulic conductivity, Young’s modulus, and Poisson’s ratio of soil materials using the uniaxial consolidation test. A nonlinear poroelastic model is presented, and the settlement data from consolidation tests are fitted to the model at each load step with the least-squares error method to inverse the parameters. The model results perfectly fit the experimental data in the initial load steps but slightly deviate from the data in later load steps as a result of secondary settlement and a largely increased Young’s modulus. The inversed parameters are compared with those calculated from the uniaxial consolidation test and those found in the literature. The comparison results demonstrate that the inversed parameters are reasonable. The proposed method provides both an estimation of parameters and the parameter-change information during a consolidation test. The method is simple, efficient, and versatile for obtaining poromechanical p...

In this study, the grey system GM(1,1) and the geostatistical method are initially used to predict the land subsidence of the Yunlin area in the next five years. The Yunlin County Yuanchang Element School is taken as the site example when the stochastic poroelastic model is used in the study because there is a lack of data related to land subsidence. The verification results and prediction data of the stochastic poroelastic model and the grey system are displayed. The results show that the land subsidence in the next five years as calculated based on the data obtained from the monitoring wells is 0.3 m, while 0.31 m and 0.33 m are the prediction results from the stochastic poroelastic model and grey system model, respectively. This indicates the high precision of both models in predicting land subsidence. In order to simulate the effect of climate change on territorial planning, a prediction is made on the possible land subsidence for 2030, in this study. The prediction results are shows that by 25 January 2030, the stochastic poroelastic model shows a land subsidence of 1.01 m, while it is 1.68 m for the Grey System model. Because only the Changyuan Element School is taken as an observation station for the stochastic poroelastic model, the Grey System model is used to predict land subsidence for 2007 by the geostatistical method. The results show that land subsidence will mainly occur in the mid-western area of Yunlin and the western coastal area of Jianyi. To simulate the possible situations in the year 2030, four scene simulation models are proposed in this research, that is, adding 10% discharge, adding 20% discharge, subtracting 10% discharge, and subtracting 20% discharge. The results show the prediction on land subsidence for the year 2003 when add 10% discharge, subtract 10% discharge, add 20% discharge, and subtract 20% discharge, respectively. Land subsidence will occur mainly in the mid-western area of Yunlin and the western coastal area of Jiayi. The maximum land subsidence could reach up to 150 cm or so.

This research attempted to investigate the consumer perceptions on product quality, price, brand leadership and brand personality towards convenience goods and shopping goods based on international private labels (IPLs) and local private labels (LPLs). Data were collected outside the entrances of the main rail station of Taipei, Taiwan. A systematic sampling was adopted and 254 questionnaires were eventually collected. The findings revealed that the consumers in Taiwan believe that international and local hypermarkets both produce better convenience goods than shopping goods that have high quality and deliver more value. This research represents one of the few pioneer works that empirically investigate the aforementioned issues. Key words: International private label, local private label, convenience goods, shopping goods.

The proposed single-inductor dual-output (SIDO) converter with interleaving energy-conservation mode (IECM) control is designed using 65 nm technology to power the ultra-wide band (UWB) system. The energy-conservation mode (ECM) control generates four different energy delivery paths for dual buck outputs with only one inductor. In addition, the superposition technique is used to achieve a minimized inductor current level. The average inductor current is equal to the summation of two output loads. Moreover, the IECM control activates the interleaving operation through the current interleaving mechanism to provide large driving capability as well as to reduce the output voltage ripple. As a result, 91% peak efficiency is derived and the output voltage ripple appears notably minimized by 50% using current interleaving at heavy load. The test chip occupies 1.44 mm2 in 65 nm CMOS and integrates with a three-dimensional (3-D) architecture for inductor integration.

The interaction of geomechanics and flow within a soil body induces deformation and pore pressure change. Deformation may change hydrogeological and elastic properties, which alters the mechanical behaviour and results in non-linearity. To investigate this interaction effect in a heterogeneous porous medium, a stochastic poroelastic model is proposed. Monte Carlo simulations are performed to determine the mean and uncertainty of the parameter changes, displacement, and change in pore water pressure. Hydraulic conductivity is treated as the only random variable in the coupled geomechanics-flow system due to its large variation compared to other mechanical and hydrogeological properties in natural environments. The three considered non-linear models for the interaction between parameters and deformation are those that consider (1) porosity and hydraulic conductivity; (2) porosity and Young's modulus; and (3) a combined effect that includes porosity, hydraulic conductivity, and Young's modulus. Boundary effects on the coupled system are also explored. The relationships between changes of porosity, hydraulic conductivity, and Young's modulus are analytically shown to be non-linear. Among the considered parameters, the deformation effect induces the largest reduction in hydraulic conductivity. The deformation-induced change in hydraulic conductivity shows the most significant effect on the mean and variance of the change in pore water pressure and displacement, while changes in Young's modulus have the least effect. When the deformation effect is considered, the superposition relationship does not exist in the mean displacement and mean change in pore water pressure for the three scenarios considered; it exists for the case without deformation effects. Deformation also causes a reduction in the effective hydraulic conductivity for the whole domain. The scenario that considers both loading and discharge boundaries has larger changes in hydrogeological and geo-mechanical parameters than those in scenarios that consider loading and discharge boundaries separately. The results indicate that the interaction between deformation and changes in parameters has a profound effect on the poroelastic system. The effect of deformation should thus be considered in modelling and practice. Copyright © 2009 John Wiley & Sons, Ltd.

Summary In this study, a stochastic model is proposed to solve poroelastic problems in heterogeneous porous media. The model is constructed using the first-order second-moment method to investigate the dynamic behaviors of statistical mean and covariance of the change in pore water pressure and displacement. Although several variables can be simultaneously treated as random in the model, the Darcy conductivity is selected as the only random variable for this preliminary investigation due to its large variation compared to other mechanical and hydrogeological properties in natural environments. The constructed model is general in multiple dimensions; however, the one-dimensional case is taken as an example to demonstrate the use of the stochastic model. This model is validated using analytical and numerical solutions from the literature. Numerical experiments are then performed to investigate the boundary effects on the coupled fluid pressure and mechanical deformation in elastic porous media. The results show that the dynamic behavior of a coupled flow–stress system is more complex than a system that does not consider the deformation of porous media. Loading effects on deformation and pore pressure are instantaneous while the effect of discharge takes time to propagate from the boundary through the whole domain. Both loading and discharge boundary conditions can significantly affect the uncertainty of the system response. In the scenario combining loading at the top boundary and discharge at the bottom boundary, the mean total settlement and the average flux satisfy the relationship of superposition to be the sum of the separated effects of loading at top boundary and discharge at bottom boundary, but the variances do not. The proposed stochastic poroelastic method can be applied to hydrological issues that concern the interaction of flow and geomechanics.

Combating the intersymbol interference is an important issue in single-carrier block transmission systems. In this paper, we present a nonlinear equalizer that combines frequency-domain (FD) prefiltering with time-domain tree search detection. Simulation results show that the proposed algorithm achieves a detection performance that is very close to that of the conventional tree search equalizer (which employs the QRD-M algorithm), but with a much lower complexity. In addition, the proposed algorithm performs significantly better than the linear equalizers and decision-feedback equalizers, with only a modest increase in complexity.

This interleaving energy-conservation mode control for single-inductor dual-output converter uses the superposition technique to yield the optimal average inductor current and 91% peak efficiency. Neither a freewheel stage nor a post-regulator is needed at nominal conditions. The output voltage ripple appears notably minimized over 50% by means of current interleaving at full load. The chip occupies 1.44 mm2 in 65 nm CMOS and integrates with a 3D architecture for ultra-wide band system.

A trade-off performance between static error and dynamic response is made by the combination of proportional (P) and proportional derivative (PD) compensations. Owing to the fast transient response provided by the P compensator, the static error is also reduced by the PD compensator within a reasonable response time. The proposed control circuit is entirely implemented by voltage mode and has better line and load regulations. An asynchronous 1.8MHz DC/DC boost converter was fabricated by UMC 0.35mum to generate 35V output voltage to turn on more than 10 LED at the same time for the notebook's backlight.

A load dependent proportional-integration (PI) compensation is proposed in this paper for minimizing transient dropout voltage and accelerating the transient response of current mode DC-DC converters. The adaptive compensation resistance and capacitance are used to react to the sudden load variations: At the beginning of load transient response, the adaptive compensation capacitance is decreased to move the compensation pole-zero pair to a higher frequency for achieving fast transient response. At the end of load transient response, the pole-zero pair is moved back to an optimal position for extending the system bandwidth and phase margin based on the instant load condition. Simulation results demonstrate the excellent performance at transient period and steady-state with this proposed fast transient control and adaptive pole-zero compensation. The overshoot/undershoot voltage is smaller than 45mV and transient period is shorter than 15us as load current suddenly changes between 100mA and 500mA.

This paper proposes a design methodology for implementing a high efficiency and/or a low cost RGB backlight module in color sequential notebook computers' display. A RGB LED driver composed of an asynchronous 1.5MHz DC/DC boost converter with dual loop control is fabricated by TSMC 0.25 μm BCD 40V to generate 17V or 21V output voltage to turn on more than 6 series-red, 6 series-green, or series-blue LEDs at the same time for the notebooks' backlight. Besides, charge-recycling technique is used to restore extra energy at the output node when switching to different forwarding light emitting diodes (LEDs) and release the energy next time. The total power consumption of a 15.4′ LCD panel of a notebook computer can be reduced from 5W to about 2–3W.