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This study introduces a novel large three-dimensional physical model experimental system (PMES) for studying the geomechanical problems related to deep underground engineering. The apparatus is mainly composed of a counterforce frame, a hydraulic loading subsystem, a sample installation and transportation subsystem, an excavation subsystem, an integrated monitoring subsystem, and auxiliary facilities. During the design and development of the PMES apparatus, key technological issues were addressed. A high-stiffness frame structure with opening and closing function was developed. Uniform, gradient, and designed non-uniform stresses can be applied with high accuracy. An independent long-term load-holding unit and a surface dynamic disturbance unit were designed. The basic and innovative functions of the apparatus were verified through calibration experiments. A large physical model experiment was conducted to simulate the excavation of a deep-buried drainage tunnel in China's Jinping-II hydropower station. The experiment obtained the failure processes of the surrounding rock masses induced by high in-situ stress, specific engineering geological structures and excavation disturbance. The internal fracturing and strain evolution within the sample were successfully captured by the integrated monitoring subsystem. The results also validated the reliability of this novel apparatus. The development of this novel apparatus provides a new tool for the study of geomechanical problems in deep underground engineering. Highlights: A novel large three-dimensional physical model experimental system for studying the geomechanical problems related to deep underground engineering was established. The basic and innovative functions of the apparatus were verified through calibration experiments. A large physical model experiment was conducted to simulate the excavation of a deep tunnel in China's Jinping-II hydropower station. [ABSTRACT FROM AUTHOR]

Heat transfer in jointed rock masses exhibits characteristics of discontinuous, heterogeneous, and anisotropic due to the effects of rock discontinuities. In this work, thermal contact resistance (TCR) evolution of granite joints under normal stress was investigated. A novel method was proposed for the measurement of TCR for rough rock joints. A numerical calculation program was established for the determination of contact area based on the initial morphology of the joint surfaces and the monitored joint closure during the experiment. An estimation model of TCR for granite joints based on the equivalent joint aperture was established. It is found that TCR of granite joints shows decreasing trend with normal stress. The decreasing rate is relatively large at the initial loading stage and gradually reduces with normal stress. The values of TCR eventually stabilize. TCR of granite joint has no obvious correlation with joint roughness coefficient. It is more significantly affected by the contact area. Plastic deformation and rupture of the micro-convex body on the joint surfaces occurred due to the application of normal stress, which improve the heat transfer efficiency and lead to the decrease in TCR. In general, predication results of the TCR estimation model show good consistency with the experimental data. The model is more suitable for the cases with small joint apertures. This study can provide knowledge to the better understanding of heat transfer in rock masses containing different kinds of discontinuities. Highlights: A novel method was proposed for the measurement of thermal contact resistance for rough rock joints. A numerical calculation program was established for the determination of contact area for rough rock joints. Evolution of thermal contact resistance with normal stress and joint contact area was obtained and analyzed. An estimation model of thermal contact resistance for granite joints based on the equivalent joint aperture was established. [ABSTRACT FROM AUTHOR]

This study presents the results of investigation on thermal conductivity anisotropy of a typical kind of thinly interbedded rock, i.e., banded magnetite quartzite. Influence mechanism of main factors on the thermal conductivity anisotropy were studied through experimental and numerical approaches. Using optical scanning technique, distributed thermal conductivity on the sample surface was obtained through a series of parallel scanning lines. Based on the measured distributed thermal conductivity graphs, effects of the spatial location and geometric size of the analysis subdomain on the thermal conductivity anisotropy were investigated. The results indicated that local anisotropy factors calculated based on subdomains with different spatial locations show significant heterogeneous characteristics. The spatial inhomogeneity of anisotropy is mainly influenced by local variations of mineral bands thickness, visible fissure development and its orientation relation with bedding planes. With the increase of geometric size of analysis subdomain, the dispersion degree of the local anisotropy factors gradually reduced. Based on thermal contact theory, a finite element model was established to simulate the thermal conduction processes of thinly interbedded rocks and its anisotropic characteristics. The numerical model was calibrated based on the experimental results. Sensitivity analysis was performed to investigate the effects of main model parameters on the thermal conductivity anisotropy. The results of this study can provide better knowledge to the anisotropic thermal properties of interbedded rock masses. [ABSTRACT FROM AUTHOR]

In this work, effective thermal conductivity (λEff) of fractured rock masses was numerically investigated. A two-dimensional Discrete Fracture Network (DFN) model of the fractured rock masses was established based on the statistic results of natural fracture development in a potential area for high level radioactive waste disposal in China. Steady state heat transfer processes in the fractured granite rock masses were numerically simulated using finite element method (FEM). The calculated λEff values of the fractured granite rock masses in dry and saturated conditions are 1.99 W/(m K) and 2.31 W/(m K), respectively. Compared with the thermal conductivity of intact granite [λIntact, 2.5 W/(m K)], the drop rates are 20.4% and 7.6%, respectively. Sensitivity analysis was conducted on the main model parameters including fracture density (FDensity), trace length (FLength), thermal contact resistance (FTCR), and λIntact. The results indicate the relation between λEff and three fracture parameters (FDensity, Flength and FTCR) can be fitted using power law or negative exponent functions with good consistency. When fracture network parameters remain unchanged, λEff is in linear positive correlation to λIntact. The slop of the fitted line is determined by the fracture network parameters. Due to the fact that distribution of generated fractures in different directions are quite uniform, λEff did not show significant difference in different directions. On the basis of the above-mentioned results, an estimation model was proposed for the determination of λEff of fractured rock masses using P21 (total length of fracture traces per unit area), FTCR, and λIntact. The proposed estimation model shows good consistency to the calculated results of FEM model. [ABSTRACT FROM AUTHOR]

The prediction of active earth pressure was generally implemented under the assumptions of two-dimensional conditions and cohesionless soils. However, in practice, the soils usually display a considerable level of cohesion, and the collapse of retained slopes exhibits a three-dimensional (3D) nature. Considering this fact, this paper intends to predict the 3D active earth pressure in cohesive soils based on the kinematic limit-analysis method and a 3D rotational collapse mechanism. The influence of cracks is considered, including a crack forming before the failure of retained soil masses (open crack) and a crack forming simultaneously with the failure (formation crack). The active earth pressure coefficient is estimated based on the work-energy balance principle. In order to facilitate direct application, several design charts are provided. It is shown that accounting for soil cohesion and 3D effects results in a notable decrease in the active earth pressure, whereas considering the existence of cracks would increase the pressure value. This paper develops the studies on active earth pressure, which considers the presence of cohesion, cracks, and 3D effects together for the first time. The results of this paper can offer references in designs of retaining structures for cohesive slopes. [ABSTRACT FROM AUTHOR]

Lungs are the primary metastatic sites for osteosarcomas responsible for associated mortality. Recent data has documented role of long non-coding RNAs (lncRNAs) in proliferation and growth of osteosarcoma cells. We evaluated a role of lncRNAs in the lung metastasis of osteosarcoma with the goal of identifying a unique signature. Comparison of different lncRNAs in tumor samples from osteosarcoma with and without lung metastasis led to identification of MALAT1 as the most differentially upregulated lncRNA in the osteosarcoma patients with lung metastasis. MALAT1 was also high in osteosarcoma cells KRIB and MALAT1's targeted downregulation in these cells led to decreased invasive potential and identification of miR-202 as the miRNA that is sponged by MALAT1. In the lung metastasis in vivo model, parental KRIB cells metastasized to lungs and such metastasis was significantly inhibited in KRIB cells with downregulated MALAT1. Ectopic miR-202 expression attenuated KRIB downregulation-mediated effects on lung metastasis. In yet another in vivo model involving parental SAOS-2 and lung-metastatic derivatives SAOS-2-LM, MALAT1 expression was found to be elevated in lung metastatic cells, which also correlated with reduced miR-202. In conclusion, MALAT1-miR-202 represents a potential lncRNA-miRNA signature that affects lung metastasis of osteosarcomas and could potentially be targeted for therapy. [ABSTRACT FROM AUTHOR]

In this work, the effect of mechanical damage on the thermal conductivity of granite was experimentally investigated. Granite samples were artificially damaged through cyclic loading and unloading tests, with the strain evolution and acoustic emission activity monitored simultaneously. P-Wave velocity of the damaged samples was tested to evaluate the damage effect. Thermal conductivity of the undamaged and damaged granite samples was tested using optical scanning method. The influence of mechanical damage on thermal conductivity was analyzed. Thermal conductivity difference in different testing directions was analyzed based on the experiment results in six scanning lines on the two surfaces of each disk sample. The results indicate that thermal conductivity of damaged samples reduced compared with that of the undamaged samples, while the thermal inhomogeneity factor increased. Thermal conductivity increased in water-saturated condition for both undamaged and damaged samples. The increased rate of damaged samples was bigger than that of the undamaged samples. The mechanical damage treatment caused the increase in the thermal conductivity difference in different testing directions. The difference decreased when samples were water saturated. Research results in this work can provide better knowledge to the evolution mechanism of thermal conductivity of engineering rock masses. [ABSTRACT FROM AUTHOR]

Probing primordial gravitational waves is one of the core scientific objectives of the next generation CMB polarization experiment. Integrating more detector modules on the focal plane and performing high accurate observations are the main directions of the next generation CMB polarization telescope, like CMB S4. Also, multi-band observation is required by foreground analysis and reduction, as it is understood that foregrounds have become the main obstacles of CMB polarization measurements. However, ground observation is limited by the atmospheric window and can be usually carried out in one or two bands, like what BICEP or Keck array have done in the south pole. In this paper, we forecast the sensitivity of tensor-to-scalar ratio r that may be achieved by a multi-frequency CMB polarization experiment, basing on which to provide guidance for further expanding frequency bands and optimize the focal plane of a telescope. At the same time, the realization of having two frequency bands in one atmospheric window is discussed. With fixed number of detectors, the simulation results show that, in order to get a good limit, more frequency bands are needed. Better constraints can be obtained when it includes at least three bands, i.e., one CMB channel (95 GHz) + one dust channel (high frequency) and one synchrotron channel (low frequency). For example, 41 + 95 + 220 GHz, which is better than only focusing around the CMB band, like 85 + 105 + 150 GHz, and 95 + 135 + 155 GHz, and this frequency combination is even better than the combination of 41 + 95 + 150 + 220 GHz. As CMB S4 plans to consider two frequency bands in each atmospheric window, and along this way, we find that one CMB band and more bands in synchrotron and dust channels are helpful, for example, 2 bands in lower frequency, 30 + 41 GHz, 2 bands in higher frequency, 220 + 270 GHz, i.e. 30 + 41 + 95 + 220 + 270 GHz, can get better constraints, and in this case, more detectors are asked to be assigned in the CMB channel. [ABSTRACT FROM AUTHOR]

Based on the frequent occurrence of stress-induced hazards in deep rock tunnels, a physical model experimental study of the development process, failure mechanism, and onset conditions of deep hard rock spalling in horseshoe-shaped tunnels is carried out. The test process mainly includes model preparation, loading, excavation, and monitoring. A high-speed camera, distributed fiber optic sensing, acoustic emission (AE) system, and visual imaging correlation-2D (VIC-2D) techniques are integrated to monitor the mechanical response of the surrounding rocks. The test results indicate that the physical model test successfully simulates the spalling phenomena of the deep hard rock. The integrated monitoring system successfully captures the information on deformation, AE signals, and crack propagation in the instantaneous process of the surrounding rock spalling failure, which provides a sound basis for a more comprehensive understanding of the mechanism. Microcracks and dilation appear first on the sidewall surface; the cracks then continue to propagate and coalesce, forming thin rock flakes and spalling in a lamellar manner from shallow to deep. The quantitative relationships between the onset stresses, the critical strains, and the initial boundary stresses of the spalling failure are established. At the same depth from the excavation boundary, the radial strain of the sidewall is larger than that of the crown, and it decreases away from the excavation boundary to the interior. The increasing loading in vertical direction leads to the stress concentration in the shallow part at the sidewall and a sharp increase of deformation. There is a positive correlation between the spalling failure degree and the initial boundary stresses. [ABSTRACT FROM AUTHOR]

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The common practice in understanding some puzzling geotechnical and geomechanical issues by large-scale three-dimensional physical model tests is recently much improved by the introduction of 3D-printing technology which can realize the reconstruction of complex geological structures. However, during 3D printing process, the regular rock-like material suffers from some general problems such as short initial setting time, water segregation, decreasing fluidity induced by chemical reaction, and some other unclear influencing factors. To promote further development of physical model via 3D printing method and to fabricate large-scale high-precision 3D geological models, in this paper, the flow characteristics of rock-like materials were first investigated using a new fluidity testing apparatus. Based on the test results, a novel 3D-printing technology of geological material was formulated. Then, the technologies of fabricating the desired structural specimens, acquiring samples with mechanical properties and cracking behaviors similar to natural rock, printing large-scale complex geological models were formulated. The results show that the 3D-printing technology of geological materials had a principle: no losing fluidity during printing time. The parameters of print head diameter, line width, line span, and line slump were the four key factors affecting desired structural samples. From the enlightenment of printing small-scale sample, the printing methods of complex large-scale geological models including decreasing printing time, acquiring heterogeneous geological model with inner structures, desired density, and surrounding smooth surface were proposed. [ABSTRACT FROM AUTHOR]

The rockburst and spalling problems encountered in the Jinping Underground Laboratory are to be investigated using 3-D physical model testing. New similarity relationships for the brittleness, brittle–ductile transition and ductility characteristics of deep hard rock are first established based on the characteristics of the deep rock mass, thereby providing guidance for the development of analog materials with new characteristics that are appropriate for investigating deep rock engineering disasters via large-scale 3-D physical model tests. Achieving similarity simultaneously among the multiple physical–mechanical properties of deep hard rock constitutes the major challenge of research on analog materials. Consequently, a new method for designing analog materials by controlling the aggregate characteristics is proposed. The test results indicate that the aggregates of the analog materials can be controlled to achieve properties that are similar to those of the original rock. The newly developed analog material exhibits basic mechanical parameters and properties that are similar to those of Jinping marble, including high strength, high brittleness, and high unit weight in addition to brittle–ductile transition and ductility characteristics and deformation and failure modes. The new analog material successfully simulates the major physical–mechanical properties of Jinping marble and overcomes the limitations of preexisting methods, which develop analog materials via cementing agents, in which the achievement of similarity simultaneously among multiple properties is impossible. [ABSTRACT FROM AUTHOR]

The presences of tension cracks and pore-water pressure will reduce the stability of a soil-wall system. This study develops a kinematical approach to analyze how the active earth thrust is influenced by tension cracks and pore-water pressure, using the powerlaw nonlinear yield criterion. Although many cracks may be present in the backfill, this paper only involves one crack which leads to the most unfavorable effect. The influence of pore-water pressure is also considered using the concept of pore-water pressure coefficient. The power-law yield criterion is adopted characterize the soil strength, and the generalized tangential technique is introduced to realize the transition to the conventional linear problem. An objective function for the active earth thrust is derived from the equilibrium of rates of work and energy. Numerical results are determined from a maximization programming. By comparing with the available solution, the presented solution is validated. The results show that the presence of cracks has an unfavorable influence of increasing the active earth thrust, and this effect is even more obvious when the impact of seepage pressure is considered. [ABSTRACT FROM AUTHOR]

Objective: To analyze the effect of Chinese medicine (CM) on mortality and quality of life (QOL) of acquired immunodefificiency syndrome (AIDS) patients treated with combined antiretroviral therapy (cART).Methods: A random sample of AIDS patients enrolled in the National Chinese Medicine Treatment Trial Program (NCMTP) that met the inclusion criteria was included in this study. NCMTP patients were included as the CM+cART group, and those not in the NCMTP were included as the cART group. Survival from September 2004 to September 2012 was analyzed by retrospective cohort study. QOL was analyzed by cross-sectional study.Results: The retrospective cohort study included 528 AIDS patients, 322 in the CM+cART group and 206 in the cART group. After 8 years, the mortality in the CM+cART group was 3.3/100 person-years, which was lower than the cART group of 5.3/100 person-years (P<0.05). The hazard ratio (HR) for mortality in the cART group was 1.6 times that of the CM+cART group by Cox proportional hazard model analysis. After controlling for gender, age, marital status, education, and CD4+ T-cell count, the HR was 1.9 times higher in the cART group compared with the CM+cART group (P<0.05). The cross-sectional study investigated 275 AIDS patients. The mean scores of all QOL domains except spirituality/personal beliefs were higher in the CM+cART group than in the cART group (P<0.05).Conclusions: For AIDS patients, CM could help to prolong life, decrease mortality, and improve QOL. However, there were limitations in the study, so prospective studies should be carried out to confifirm our primary results. [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoates (PHAs) are promising alternatives to plastics since they have similar properties to polyolefin but are biodegradable and biocompatible. Recently, the conversion of propionate wastewater to PHAs by undefined mixed microbial cultures becomes attractive. However, how microbial community changes remains unclear during the enrichment step, which is critical for a robust PHA-producing system. In this study, PHA-accumulating cultures were enriched under feast/famine condition using propionate-rich substrates. Our results showed that during the first 2 h of the enrichment, dissolved oxygen of cultures increased remarkably until saturation, and amounts of C, N, and chemical oxygen demand of cultures decreased significantly to a very low level. High-throughput sequencing revealed that bacterial populations affiliated with Alphaproteobacteria and Bacteroidetes dominated the cultures enriched. Most of these dominant populations contributed to the conversion of short-chain fatty acids to PHAs. Being fed with the substrate rich in propionate but without nitrogen, the cultures enriched could accumulate nearly 27% PHAs at 72 h with higher content of hydroxyvalerate. Our work reveals the process in which environmental microbes responded to propionate-rich condition and shifted to populations for accumulating PHAs; it also will be helpful to develop an efficient PHA-producing system using propionate-rich waste. [ABSTRACT FROM AUTHOR]

Schwann cells (SCs) are unique glial cells in the peripheral nerve and may secrete multiple neurotrophic factors, adhesion molecules, extracellular matrix molecules to form the microenvironment of peripheral nerve regeneration, guiding and supporting nerve proliferation and migration. Cdc42 plays an important regulatory role in dynamic changes of the cytoskeleton. However, there is a little study referred to regulation and mechanism of Cdc42 on glial cells after peripheral nerve injury. The present study investigated the role of Cdc42 in the proliferation and migration of SCs after sciatic nerve injury. Cdc42 expression was tested, showing that the mRNA and protein expression levels of Cdc42 were significantly up-regulated after sciatic nerve injury. Then, we isolated and purified SCs from injuried sciatic nerve at day 7. The purified SCs were transfected with Cdc42 siRNA and pcDNA3.1-Cdc42, and the cell proliferation, cell cycle and migration were assessed. The results implied that Cdc42 siRNA remarkably inhibited Schwann cell proliferation and migration, and resulted in S phase arrest. While pcDNA3.1-Cdc42 showed a contrary effect. Besides, we also observed that Cdc42 siRNA down-regulated the protein expression of β-catenin, Cyclin D1, c-myc and p-p38, which were up-regulated by pcDNA3.1-Cdc42. Meanwhile, the inhibitor of Wnt/β-catenin and p38 MAPK signaling pathway IWP-2 and SB203580 significantly inhibited the effect of pcDNA3.1-Cdc42 on cell proliferation and migration. Overall, our data indicate that Cdc42 regulates Schwann cell proliferation and migration through Wnt/β-catenin and p38 MAPK signaling pathway after sciatic nerve injury, which provides further insights into the therapy of the sciatic nerve injury. [ABSTRACT FROM AUTHOR]

Collapse shape of tunnel floor in Hoek-Brown rock media is investigated with the functional catastrophe theory. The stability of rock system in tunnel floor, which is determined by thickness, half collapse width, half length of cave and detaching curve, has great secure and economic significance in practical engineering. To investigate the failure mechanisms and the outline of detaching block, a reliable damage model is presumed by making reference to the limit analysis theory. The analytical solutions of detaching curve, half collapse width on tunnel floor and the critical and maximum values of collapse thickness are derived based on Hoek-Brown criterion and functional catastrophe theory. The result shows that 0.5 is a most probable condition for instability, and the shape of detaching curve is a part of parabola. It is reasonable by comparing with previous theory and analogous experiments. The effects of major factors on thickness and half collapse width are further discussed. Numerical calculations and parametric analysis are carried out to illustrate the effects of different parameters on the mechanism, which is significant to the stability analysis of tunnel floor in rock media. [ABSTRACT FROM AUTHOR]

The histopathological features of the middle cerebral artery (MCA) and superficial temporal artery (STA) from moyamoya disease (MMD) and their relationships with gender, age, angiography stage were explored. The causes and the clinical significance of vasculopathy of STA were also discussed. The clinical data and specimens of MCA and STA from 30 MMD patients were collected. Twelve samples of MCA and STA from non-MMD patients served as control group. Histopathological examination was then performed by measuring the thickness of intima and media, and statistical analysis was conducted. The MCA and STA specimens from MMD group had apparently thicker intima and thinner media than those from the control group. There was no significant pathological difference between the hemorrhage group and non-hemorrhage group, and between the males and females in MMD patients. Neither the age nor the digital subtraction angiography (DSA) stage was correlated with the thickness of intima in MCA and STA. MMD is a systemic vascular disease involving both intracranial and extracranial vessels. Preoperative external carotid arteriography, especially super-selective arteriography of the STA, benefits the selection of donor vessel. [ABSTRACT FROM AUTHOR]

Background: A previous study found that brain natriuretic peptide (BNP) inhibited inflammatory pain via activating its receptor natriuretic peptide receptor A (NPRA) in nociceptive sensory neurons. A recent study found that functional NPRA is expressed in almost all the trigeminal ganglion (TG) neurons at membrane level suggesting a potentially important role for BNP in migraine pathophysiology. Methods: An inflammatory pain model was produced by subcutaneous injection of BmK I, a sodium channel-specific modulator from venom of Chinese scorpion Buthus martensi Karsch. Quantitative PCR, Western Blot, and immunohistochemistry were used to detect mRNA and protein expression of BNP and NPRA in dorsal root ganglion (DRG) and dorsal horn of spinal cord. Whole-cell patch clamping experiments were conducted to record large-conductance Ca-activated K (BK) currents of membrane excitability of DRG neurons. Spontaneous and evoked pain behaviors were examined. Results: The mRNA and protein expression of BNP and NPRA was up-regulated in DRG and dorsal horn of spinal cord after BmK I injection. The BNP and NPRA was preferentially expressed in small-sized DRG neurons among which BNP was expressed in both CGRP-positive and IB4-positive neurons while NPRA was preferentially expressed in CGRP-positive neurons. BNP increased the open probability of BK channels and suppressed the membrane excitability of small-sized DRG neurons. Intrathecal injection of BNP significantly inhibited BmK-induced pain behaviors including both spontaneous and evoked pain behaviors. Conclusions: These results suggested that BNP might play an important role as an endogenous pain reliever in BmK I-induced inflammatory pain condition. It is also suggested that BNP might play a similar role in other pathophysiological pain conditions including migraine. [ABSTRACT FROM AUTHOR]

Bone marrow mesenchymal stromal cells (BMSCs) are the common precursors for both osteoblasts and adipocytes. With aging, BMSC osteoblast differentiation decreases whereas BMSC differentiation into adipocytes increases, resulting in increased adipogenesis and bone loss. In the present study, we investigated the effect of asiatic acid (AA) on adipocytic differentiation of BMSCs. AA inhibited the adipogenic induction of lipid accumulation, activity of glycerol-3-phosphate dehydrogenase, and expression of marker genes in adipogenesis: peroxisome proliferation-activated receptor (PPAR)γ, adipocyte fatty acid-binding protein (ap) 2, and adipsin. Further, we found that AA did not alter clonal expansion rate and expression of C/EBPβ, upstream key regulator of PPARγ, and binding activity of C/EBPβ to PPARγ promoter was not affected by AA as well. These findings suggest that AA may modulate differentiation of BMSCs to cause a lineage shift away from the adipocytes, and inhibition of PPARγ by AA is through C/EBPβ-independent mechanisms. Thus, AA could be a potential candidate for a novel drug against osteoporosis. [ABSTRACT FROM AUTHOR]

In this work, the effect of hydrological spatial variability on the heat production performance of a naturally fractured geothermal reservoir was investigated. Using the geological information of an abandoned natural gas exploration well in northern Songliao Basin, northeast China, the hydraulic properties of the fractured reservoir were studied based on DFN models. The heterogeneous distribution of reservoir hydrological properties was simulated using random field method. Evolution characteristics of production temperature, heat extraction rate, injection pressure, reservoir flow impedance, and the spatio-temporal distribution of temperature and pressure were studied. A sensitivity analysis was performed on correlation distance and coefficient of variation for the random field model. The results indicate that spatial variability of the hydrological parameters has significant influence on the heat production performance. Besides, correlation distance and coefficient of variation are two key parameters that influence the distributions of reservoir parameters and cause the variation of heat production performance in random field models. [ABSTRACT FROM AUTHOR]