Extreme Boundaries Research Articles

Estimation of Surface Soil Moisture from Thermal Infrared Remote Sensing Using an Improved Trapezoid Method

Surface soil moisture (SM) plays a fundamental role in energy and water partitioning in the soil–plant–atmosphere continuum. A reliable and operational algorithm is much needed to retrieve regional surface SM at high spatial and temporal resolutions. Here, we provide an operational framework of estimating surface SM at fine spatial resolutions (using visible/thermal infrared images and concurrent meteorological data) based on a trapezoidal space defined by remotely sensed vegetation cover (Fc) and land surface temperature (LST). Theoretical solutions of the wet and dry edges were derived to achieve a more accurate and effective determination of the Fc/LST space. Subjectivity and uncertainty arising from visual examination of extreme boundaries can consequently be largely reduced. In addition, theoretical derivation of the extreme boundaries allows a per-pixel determination of the VI/LST space such that the assumption of uniform atmospheric forcing over the entire domain is no longer required. The developed approach was tested at the Tibetan Plateau Soil Moisture/Temperature Monitoring Network (SMTMN) site in central Tibet, China, from August 2010 to August 2011 using Moderate Resolution Imaging Spectroradiometer (MODIS) Terra images. Results indicate that the developed trapezoid model reproduced the spatial and temporal patterns of observed surface SM reasonably well, with showing a root-mean-square error of 0.06 m3·m−3 at the site level and 0.03 m3·m−3 at the regional scale. In addition, a case study on 2 September 2010 highlighted the importance of the theoretically calculated wet and dry edges, as they can effectively obviate subjectivity and uncertainties in determining the Fc/LST space arising from visual interpretation of satellite images. Compared with Land Surface Models (LSMs) in Global Land Data Assimilation System-1, the remote sensing-based trapezoid approach gave generally better surface SM estimates, whereas the LSMs showed systematic underestimation. Sensitivity analyses suggested that the trapezoid method is most sensitive to field capacity and temperature but less sensitive to other meteorological observations and parameters.

Learning from the past, Looking to the Future

Abstract: This article offers a framework to aid uniformed strategic leaders in reflecting on the last decade of conflict. This framework takes into account emerging historiography, time-tested military theory, and a holistic understanding of military history to help prepare officers to offer strategic advice in the future. ********** As the black flags of the Islamic State appear in more and more places in Iraq, a new generation of officers will likely reflect on what has and has not been accomplished, and what is and is not possible through the force of arms. Conclusions about the recent era of conflict will affect US officers as they ascend to higher ranks and provide the best military advice they can to the nation's civilian leadership. These future senior leaders should not allow emotion to affect their introspection. (1) Future senior leaders must place their past service in a context that takes into account emerging historiography, time-tested military theory, and a holistic understanding of military history, as this foundation will allow them to provide better strategic advice. This article explores emerging historiography before revisiting just a few of the military theorists who continue to transcend time. It will then offer a brief overview of American military history by examining the popular outliers in the conscience of military professionals before turning to what the US military has done more often. Penultimately, it offers recommendations for how senior military leaders should approach historiography as they consider the future, and how a grounding in theory benefits them in the politically dominated realm of strategy. Last, this article suggests how to use historical context when providing advice and speaking truth to power, even when the message is not popular. As it has in the past, the US military will have to execute campaigns that lack strategic clarity or coherent policy objectives. Some campaigns will be, in the words of Andrew Bacevich, fool's errands. (2) However, armed with an inclusive view of the past, not just the highlight reel, future strategic leaders may be better able to fulfill their roles. Historiography Historiography matters because it shapes approaches used at professional military education (PME) institutions. Iconography and personal views present intellectual minefields students and faculty must navigate with civility even when dealing with interpretations of the increasingly distant American Civil War. At one time, a walk through the halls of the US Army War College could have caused one to wonder who won the war, or how the profession has chosen to remember its past. Military professionals might have to work harder to distill the lessons of emerging narratives seeking to explain the less than decisive outcomes in Iraq and Afghanistan, events in which many of them participated. (3) Easily digested Manichean explanations for enormously complicated issues deserve attention only in helping to define the extreme boundaries of the entire field. (4) How the profession remembers the last decade of conflict will likely influence the way it approaches the use of force in the future. (5) Remembering the past can be painful and complicated, as the Civil War illustrates, thus reminding the profession of the care it should take in capturing and interpreting various perspectives of recent events. Anti-COIN Gian Gentile and Douglas Porch each used historical analysis of a variety of campaigns to reach the same conclusion: counter-insurgency (COIN) doctrine rarely works, especially in the context of carrying out tasks related to nation-building for a third party. To their credit, both authors offered these perspectives before the recent emergence of ISIL. Although there seems to be little stomach for another COIN campaign, Gentile, to be certain, offers his critique for the good of the profession. His overarching fear stems from the belief the nation might try a similar venture again should it follow Field Marshal Montgomery's dictum that armed with a good plan (as prescribed by doctrine) and the right general, anything is possible. …

Long-distance autophagy

Long-distance autophagy

Tracial state space with non-compact extreme boundary

Let A be a unital simple separable C*-algebra. If A is nuclear and infinite-dimensional, it is known that strict comparison of positive elements is equivalent to Z-stability if the extreme boundary of its tracial state space is compact and of finite covering dimension. Here we provide the first proof of this result in the case of certain non-compact extreme boundaries. Additionally, if A has strict comparison of positive elements, it is known that the Cuntz semigroup of this C*-algebra is recovered functorially from the Murray–von Neumann semigroup and the tracial state space whenever the extreme boundary of the tracial state space is compact and of finite covering dimension. We extend this result to the case of a countable extreme boundary with finitely many cluster points.

Personal Accounts: Stepping Into a Crosswalk

Personal Accounts: Stepping Into a Crosswalk

An energy model for event-based control of a switched integrator

AbstractIn this paper we present a method for constructing an approximative stationary energy model of a stochastic switching system while applying event-based control. The main model used is a multi-state integrator with random switching behavior, upon event occurrence, which has been described using a continuous Markov chain. Applying event-based control has been done in the purpose of maintaining the continuous system state variable between extreme boundaries. The sojourn times and the probabilities to hit the limits have also been used for the computation of the average energy consumed during the stationary mode of the Markov chain. Mean times between intermediary stopping points and extreme limits are also provided as well as a quadratic criterion for square deviations from imposed target limits.

Gendered Spaces in Ovid's Heroides

The Roman woman traditionally inhabited the private space of the house. The women in the single Heroides, as letter-writers, are confined to this internal space. The few women who do manage to surmount the boundaries of the house do not find freedom and adventure, but even more extreme boundaries. Those who leave even the land behind are transformed into transgressive figures, morally and sexually. Ovid demonstrates that the physical world outside of the domus is gendered, and that this gendered space becomes a moral marker for a woman's sexual identity.

Capital structure decisions: research in Estonian non‐financial companies

PurposeTo investigate the relations between company‐specific financial factors and the capital structure decisions of Estonian non‐financial companies and to examine behavioral differences between companies of different sizes.Design/methodology/approachTotally 260 Estonian non‐financial companies are divided into small‐, medium‐ and large‐companies, each sample being analysed by correlation‐regression method in two aspects – impact of financial factors on static capital structure and capital structure dynamics. Companies' financial statements of 2002/2003 or 2003/2004 are used. Finally, capital structure adjustments in extreme boundaries are analyzed.FindingsCapital structure decisions among Estonian non‐financial companies are driven by the pecking order theory, the evidences supporting optimal capital structure choices in long run remain weak. The robustness of the pecking order behavior significantly differs between smaller and bigger companies.Research limitations/implicationsLimited number of companies surveyed due to hard manual work required to adjust financial accounts. Implication of findings is somewhat limited as the study covers a single country.Originality/valueThe paper helps to identify financial drivers and to understand motivations behind capital structure decisions of emerging market companies and it supplements earlier studies. Quasi‐equity debt distorts the observed capital structures. Capital structure is adjusted for operating leases and quasi‐equity debt to identify true amount put at risk and its mix between owners and external lenders.

A “HOWFARLESS” option to increase efficiency of homogeneous phantom calculations with DOSXYZnrc

This paper describes a "HOWFARLESS" transport option, which has been added to DOSXYZnrc to increase the efficiency of beam commissioning calculations in homogeneous phantoms. The algorithm speeds up charged particle transport by only considering the distance to the extreme outer boundaries of the phantom, thus eliminating the need to stop at voxel boundaries. Dose is deposited by approximating the total curved charged particle steps by two straight-line steps joined at a hinge point. Good agreement with normal simulations is achieved at all beam energies and for all practical maximum step lengths with a 1:1 mixture of approximations based on the initial position/ direction of the particle and on its final position/direction. Use of the "HOWFARLESS" option in phantom calculations for 6 and 18 MV photon beams (10 x 10 cm2 and 40 x 40 cm2 fields) from BEAMnrc-simulated accelerators increases the efficiency at the optimum photon splitting number by a factor of 2.9-5.4 when the exact EGSnrc boundary crossing algorithm (BCA) is used and by 51%-89% when the faster PRESTA-I BCA is employed. The efficiency gain due to the "HOWFARLESS" transport option increases with increasing beam energy and decreases with increasing field/dose voxel size. Efficiency improvement is greater when the efficiency of the particle source itself is not a factor, and in such cases the "HOWFARLESS" option improves the DOSXYZnrc efficiency by up to a factor of 13.1 (exact BCA) or 3.5 (PRESTA-I BCA) for photon beams, and up to a factor of 17.2 (exact BCA) or 5.2 (PRESTA-I BCA) for electron beams.

Niche‐assembly vs. dispersal‐assembly rules in coastal fish metacommunities: implications for management of biodiversity in brackish lagoons

Summary Biodiversity is rapidly being lost in a world transformed increasingly by human activities. We need to determine urgently the factors which control the coexistence of species and thus allow local biodiversity to be maintained. Coexistence between interacting species can be explained by species‐sorting, mass‐effect, patch dynamic and neutral perspectives on metacommunities. According to the first two paradigms, community assembly rules are based on species’ ecological niches or functional roles, whereas the latter two emphasize the role of stochastic processes. Here I consider whether effective strategies for managing fish biodiversity in coastal lagoons depend on the predominant paradigm. The neutral perspective was not considered relevant because lagoon fishes belong to different trophic levels and have clear niche differences. Where fish coexistence is ruled by species‐sorting, priority must be given to the preservation or restoration of habitat, whereas heterogeneity among lagoons and population densities become critical when mass effects predominate. According to the patch dynamics perspective, the key factors are individual turn‐over and the fitness equivalence among species. Synthesis and applications. Coastal fish metacommunities are not ruled consistently by a single theoretical paradigm. However, consideration of such extreme cases sets clear boundaries for species assembly rules. Confronting the three main views is not only a controversial topic, but also has consequences for ecosystem and biodiversity management.

Pressure transient analysis for long homogeneous reservoirs using TDS technique

A significant number of well pressure tests are conducted in long, narrow reservoirs with close and open extreme boundaries. It is desirable not only to appropriately identify these types of systems but also to develop an adequate and practical interpretation technique to determine their parameters and size, when possible. An accurate understanding of how the reservoir produces and the magnitude of producible reserves can lead to competent decisions and adequate reservoir management. So far, studies found for identification and determination of parameters for such systems are conducted by conventional techniques (semilog analysis) and semilog and log–log type-curve matching of pressure versus time. Type-curve matching is basically a trial-and-error procedure which may provide inaccurate results. Besides, a limitation in the number of type curves plays a negative role. In this paper, a detailed analysis of pressure derivative behavior for a vertical well in linear reservoirs with open and closed extreme boundaries is presented for the case of constant rate production. We studied independently each flow regime, especially the linear flow regime since it is the most characteristic “fingerprint” of these systems. We found that when the well is located at one of the extremes of the reservoir, a single linear flow regime develops once radial flow and/or wellbore storage effects have ended. When the well is located at a given distance from both extreme boundaries, the pressure derivative permits the identification of two linear flows toward the well and it has been called that “dual-linear flow regime”. This is characterized by an increment of the intercept of the 1/2-slope line from π 0.5 to π with a consequent transition between these two straight lines. The identification of intersection points, lines, and characteristic slopes allows us to develop an interpretation technique without employing type-curve matching. This technique uses analytical equations to determine such reservoir parameters as permeability, skin, well location and reservoir limits for both gas and oil linear reservoirs. The proposed technique was successfully verified by interpreting both field and synthetic pressure tests for gas and oil reservoirs.

Nanofiltration for oil-fields water injection operations: analysis of osmotic pressure and scale tendency

Consumption of specific energy (total energy consumed to produce a unit volume of permeate) and scale inhibitors are key factors for efficient or inefficient operation of nanofiltration (NF) (or reverse osmosis, RO) systems. To minimize energy consumption, a suitable energy recovery device must be installed to recover waste energy. Even with optimum recovery of waste energy, still energy consumption exceeds 50% of the total operating costs. The best way to minimize the cost of scale inhibitors is to prevent scale (particularly sulfate) from forming. Scale cleanup (shut-down time and cost of inhibitors and dissolvers) and membranes replacement occupy the rest of the operating costs. As such, designers of NF systems must be aware of the hydraulic and scale envelops, that are the extreme boundaries of operational parameters over the lifetime of the systems. Such boundaries are determined by two factors. The first factor is the throughput ratio, which in turn, is governed by salinity, scale tendency, and temperature. The second factor is the overall system hydraulic, which in turn, is controlled by throttling losses, array losses, and pressure drops within membranes modules. However, the focus of this analysis is the first factor. This third article, in a four-part series, provides a modeling tool to predict: (1) the actual osmotic pressure difference between the membrane surface (Π m ) rather than the bulk of the feed stream (Π F ), and the permeate stream (Π P ) taking into account the actual rejection (R a ) factor; and (2) the saturation degree of calcium sulfate dihydrate (gypsum) and strontium sulfate (celestite) at the membrane surface, and on the concentrate side of the membrane.

ChandraObservations of the W51C Supernova Remnant

We present the results of Chandra ACIS observations of the supernova remnant (SNR) W51C. The remnant is located in the cross section of the Sagittarius arm, and the Chandra images present a superb X-ray view of this complex region including the massive star-forming region W51B. The properties of thermal diffuse SNR emission are consistent with the results of previous studies except that an enhanced abundance of sulfur is required. It is found that the ASCA hard X-ray source CXO J192318.5+1403035, proposed to be a pulsar wind nebula, is composed of a relatively bright core surrounded by an extended (~7.0 × 2.5 pc) diffuse envelope. The core contains a compact (<0.1 pc) source at the center. The X-ray spectrum of CXO J192318.5+1403035 can be fitted by a power-law emission model with Γ = 1.82, and the implied X-ray (0.2-4.0 keV) luminosity is 5 × 1033 ergs s-1. The core contributes ~20% of the total luminosity. The core-envelope structure and its spectral properties support CXO J192318.5+140305 as a pulsar-wind nebula associated with the SNR W51C. There is also enhanced radio emission coincident with the source. It is conceivable that the central compact source might harbor a pulsar. However, the large extent and the hardening of X-rays at the extreme boundaries need to be explained. We have searched for the Brγ line from the ionized gas associated with the source, but no emission was detected.

Upgrade of the present JET shape and vertical stability controller

The development of linear model of the present JET (Joint European Torus) electromagnetic system has allowed the design of an optimized Plasma Shape Controller. Quite extreme plasma boundaries (elongation k=1.9 and triangularity 〈 δ〉=0.6) are shown to be controllable also in the presence of large variations of the values of poloidal beta (0.1< β p<0.6) and/or internal magnetic inductance (0.8< l i<1.4). The developed model gives also an excellent simulation of the growth rate of the experimental vertical disruptions.

Theory of magnetization: Twin boundary interaction in ferromagnetic shape memory alloys

Much interest has been recently given to the development and understanding of ferromagnetic shape memory alloys. In particular, the interaction of crystallographic twin boundaries with an external magnetic field has been put forth as a mechanism for shape deformation and applied to the alloy Ni2MnGa. In this article, we examine this interaction analytically. We consider two crystallographic variants wherein the magnetization directions at their extreme boundaries are along their easy axes. Further, we have included the magnetic exchange energy and have postulated a Gaussian strain distribution localized in one of the variants. Using the basic micromagnetic equations, we determine the magnetization distribution throughout the variants as well as the equilibrium positions of the twin boundary. We show that the resulting magnetic domain wall leads the twin boundary position as long as the magnetic driving force is insufficient to overcome the strain energy impediment. For the reverse situation, both the twin boundary and magnetic domain wall move through the opposing variant. The magnetic coercivity is correspondingly reduced.

How many species of Hexabranchus (Opisthobranchia : Dorididae) are there?

Anatomical examination of several specimens of Hexabranchus, collected from the extreme boundaries of its geographic range and other localities, revealed that there are two distinct species within this genus. One of these species is widely distributed throughout the tropical Indo-Pacific. The oldest available name for the Indo-Pacific species is Hexabranchus lacer (Cuvier, 1804). The study of the original type material of H. lacer confirmed that it is a senior synonym of other names introduced subsequently, including Hexabranchus sanguineus (Ruppell & Leuckart, 1830), which is the name most commonly used for this species. However, according to the provisions of the International Code of Zoological Nomenclature (Article 23.9.1), the name H. sanguineus has precedence over H. lacer, which has never been used as valid, except for the original description. Hexabranchus praetextus Ehrenberg, 1828 is also a senior synonym of H. sanguineus that has not been used as valid since its original description and it is also invalidated under the provisions of Article 23.9.1. The other species, Hexabranchus morsomus Ev. Marcus & Er. Marcus, 1962, appears to be endemic to the Caribbean Sea. Hexabranchus sanguineus and H. morsomus are clearly distinguishable by the morphology of the reproductive system and the radula. Hypotheses on the speciation process that took place in Hexabranchus, the possible origin of the two species and the geographic range of the genus are discussed.

Roundness modeling of machined parts for tolerance analysis

Out-of-roundness of circular and cylindrical parts can greatly affect assembly accuracy. At present, the ASME Y14.5M-1994 specifies circularity tolerance based on two extreme circular boundaries to confine the highest peak and the lowest valley of a roundness profile; however, the profile variations within the two extreme boundaries are not accounted for. In this paper, we propose a harmonic roundness model using Fourier series expansion. In addition, a cutting profile model has been developed to illustrate the relationship between the radial error motion of a spindle and the resultant part profile. This relationship is then used to provide physical meanings to the harmonics generated by the proposed roundness model for a part profile, in particular those caused by fractional frequency spindle error motions. The proposed harmonic model has been verified statistically by a large number of real profiles produced by both turning and cylindrical grinding processes. The proposed roundness model is expected to provide insights into the advanced tolerance analysis of circular and cylindrical parts.

Generalized 3D Analytical Model for Transient Flow in Compartmentalized Reservoirs

Summary A new generalized transient-flow model for a three-dimensional (3D) compartmentalized system with n compartments has been developed analytically. Each compartment may have distinct rock and fluid properties and may produce through a number of partially penetrating wells. A partially communicating fault or barrier causing poor hydraulic communication between a pair of adjoining compartments is modeled as a thin skin at the interface. Production rates and conditions at the extreme boundaries are considered to be time variant. The solution was also validated by examining a few limiting cases. An example problem with stacked channel realization was studied. A simple method for detecting the poorly drained compartments from the extended drawdown data was developed. This has also lead to an estimation of hydrocarbon-pore volume in each compartment.

Frequency responses of two- and three-tone distortion product otoacoustic emissions in Mongolian gerbils.

The frequency responses of distortion product otoacoustic emission (DPOAEs) were investigated in adult Mongolian gerbils. The main goal was to investigate in this species the extent to which DPOAE measurements might be useful in estimating cochlear frequency-tuning characteristics. Specifically, this study investigated the parameter space for generation of DPOAEs to determine those regions, if any, where the emission responses gave "simple" frequency responses, i.e., responses similar in form to typical neural responses. At the same time, it was desired to determine in this species the existence, extent, and nature of the more complex three-tone emission frequency responses as observed in some other species [e.g., Martin et al., Hearing Res. 136, 105-123 (1999)]. In the present work, two-tone frequency response curves (f2/f1 ratio functions) were obtained by varying the lower frequency, f1, while holding the f2 frequency and both amplitudes (L1, L2) constant. Only for frequencies, f2, near 8 kHz did the response at the emission frequency, 2 f1-f2, form a simple, relatively broad peak. At all lower frequencies, the two-tone frequency response curve was typically complex and composed of multiple peaks. In comparison, three-tone frequency responses were constructed by fixing the primary stimulus pair (f1, f2) and varying a third tone widely in frequency (f3) and intensity (L3). Points in f3 and L3 which caused a criterion reduction in primary emission amplitude (at 2 f1-f2) were used to construct emission suppression tuning curves (STCs). Only for primary frequencies, f2, at 8 kHz and above were the emission STCs found to be simple, with shapes similar to neural frequency-tuning curves. At lower primary frequencies, particularly for relatively low primary frequency ratios (low f2/f1), three-tone responses were very complex. This complex response usually included a region of anomalous suppression in which very low suppression levels (L3) could result in significant decreases in the primary emission amplitude, often exceeding 12 dB. Regions of such anomalous suppression were typically observed under the following conditions: (1) for all f2 frequencies from 0.5 to 4 kHz; (2) for f3 frequencies between 1.4 and 8 kHz; (3) i.e., for f3 frequencies 1-3 octaves above the primary frequency, f2; (4) at L3 levels often 10 dB lower or more than the usual "best frequency" threshold, i.e., even lower than the relative minimum threshold found near the primary stimulus frequencies; (5) exhibiting sharp amplitude decreases often accompanied by emission phase shifts of about 180 deg; (6) present in both cubic emissions (2 f1-f2 and 2 f2-f1); (7) to be less extreme at larger primary stimulus frequency ratios (larger f2/f1); and (8) less extreme at larger intensity ratios (larger L1/L2). Because of the anomalous behavior at f2 frequencies below 8 kHz, "simple" emission STCs were typically only obtainable, if at all, near the extreme boundaries of the parameter space giving measurable emission amplitudes.

A Generalized, Transient Flow Model For Linear, Compartmentalized Systems

Abstract Fluid flow in narrow reservoirs or aquifers is predominately linear. However, this linear-flow system may possess variations in rock and fluid properties and/or presence of faults due to a number of geological phenomena. Such systems are modelled as linear, compartmentalized systems. In this study, a new generalized transient-flow model has been developed analytically for an n-region compartmentalized system. Each compartment or region may have distinct rock and fluid properties. A time-dependent production rate from each compartment is modelled in a general way. The conditions at the extreme boundaries are taken as non-homogeneous, time-dependent, Cauchy-type that can be modified to Dirichlet- or Neumann-type as a special case. A possible situation of poor communication between neighboring compartments has been incorporated into the model by considering the presence of a thin skin at each interface. A generalized solution for the dimensionless pressure has been derived using an integral-transform technique. This solution deals directly with situations like production rates and extreme boundary conditions being time-dependent without the need for using the principle of superposition in time or Duhamel's principle. Some limiting cases of this new solution have been used for validation purposes. Several advantages and practical applications of this model are also discussed. Introduction The flow of fluids through narrow reservoirs or aquifers is predominantly linear. However, this linear-flow system may possess variations in rock and fluid properties and/or faults due to geological phenomena. Levorsen(1) mentioned that the extent of a reservoir boundary may be sharp or it may be gradationa, as is more often the case. This heterogeneous character of a reservoir makes it difficult to model. To alleviate the mathematical difficulties of modelling such a system, the concept of compartmentalization may be used. With this concept, a heterogeneous system is assumed to be comprised of a number of homogeneous compartments. The communication of fluid between adjoining compartments may be hindered due to the presence of faults or any other barriers. Ehlig-Economides and Economides(2) have pointed out that there are several depositional environments showing possible oil- and gas-reservoir geometries that result in predominantly linear flow. These formations, which generally have long, narrow shapes, may be the result of river meander point bars, oxbow lakes, river channels, or tectonic breccias. However, such systems may also be compartmentalized due to variations of rock and fluid properties and the presence of faults and, therefore, can be modelled as linear, compartmentalized systems. In the literature, a number of studies of linear, one-dimensional flow systems are related to homogeneous reservoirs or aquifers(3, 4, 5). Nutakki and Mattar(6) generated transient pressure responses using the line-source solution with the principle of superposition for an infinitely long, narrow, homogeneous channel. They also developed a method to determine the time to the end of the radialflow period and the beginning of the linear-flow period. Ehlig- Economides and Economides(2) have presented the techniques for interference, drawdown and buildup analysis for an elongated linear flow system.