Nominal Counterparts Research Articles

Distributionally Robust Portfolio Optimization under Marginal and Copula Ambiguity

AbstractWe investigate a new family of distributionally robust optimization problem under marginal and copula ambiguity with applications to portfolio optimization problems. The proposed model considers the ambiguity set of portfolio returns in which the marginal distributions and their copula are close—in terms of the Wasserstein distance—to their nominal counterparts. We develop a cutting-surface method to solve the proposed problem, in which the distribution separation subproblem is nonconvex and includes bilinear terms. We propose three approaches to solve the bilinear formulation, namely (1) linear relaxation via McCormick inequalities, (2) exact mixed-integer linear program reformulation via disjunctive inequalities, and (3) inner approximation method via a novel iterative procedure that exploits the structural properties of the bilinear optimization problem. We further carry out a comprehensive set of computational experiments with distributionally robust portfolios featuring Conditional Value-at-Risk (CVaR) measures. These tests aim to compare the accuracy of the proposed algorithms, analyze the impact of the radius of the Wasserstein ambiguity ball on the portfolio, and assess portfolio performance. We use a rolling-horizon approach to conduct the out-of-sample tests, which show the superior performance of the portfolios under marginal and copula ambiguity over the equally weighted and ambiguity-free Mean-CVaR benchmark portfolios.

Pattern characterization using topological data analysis: Application to piezo vibration striking treatment

Quantifying patterns in visual or tactile textures provides important information about the process or phenomena that generated these patterns. In manufacturing, these patterns can be intentionally introduced as a design feature, or they can be a byproduct of a specific process. Since surface texture has significant impact on the mechanical properties and the longevity of the workpiece, it is important to develop tools for quantifying surface patterns and, when applicable, comparing them to their nominal counterparts. While existing tools may be able to indicate the existence of a pattern, they typically do not provide more information about the pattern structure, or how much it deviates from a nominal pattern. Further, prior works do not provide automatic or algorithmic approaches for quantifying other pattern characteristics such as depths’ consistency, and variations in the pattern motifs at different level sets. This paper leverages persistent homology from Topological Data Analysis (TDA) to derive noise-robust scores for quantifying motifs’ depth and roundness in a pattern. Specifically, sublevel persistence is used to derive scores that quantify the consistency of indentation depths at any level set in Piezo Vibration Striking Treatment (PVST) surfaces. Moreover, we combine sublevel persistence with the distance transform to quantify the consistency of the indentation radii, and to compare them with the nominal ones. Although the tool in our PVST experiments had a semi-spherical profile, we present a generalization of our approach to tools/motifs of arbitrary shapes thus making our method applicable to other pattern-generating manufacturing processes.

Worst-case analysis of Omega-VaR ratio optimization model

The Omega ratio, a performance measure that separately considers upside and downside deviations from a fixed threshold, improves the Sharpe ratio by incorporating the higher-order moments. In this paper, we analyse the performance of a robust optimization model based on maximizing the worst-case of Omega ratio by taking its threshold point as the robust value of a defined percentile of the underlying loss distribution. To this aim, the threshold point is computed as the worst-case of the value-at-risk at a particular confidence level. We formulate robust model of the proposed strategy under two cases of uncertainty sets, the mixture distribution uncertainty and the box uncertainty. We show that, in the first case, the problem reduces to a second-order cone program (SOCP) and, in the second one, to a semi-definite program (SDP), hence tractable in both the cases. We conduct a comprehensive empirical investigation of the proposed models over six data sets across the globe, namely BSE 100 (India), FTSE 100 (UK), Hang Seng (Hong Kong), S&P Asia 50 (Asia), Dow Jones Industrial Average (USA), and IBEX (Spain). We compare our models with the three variants of the Omega ratio model, one its robust variant taking worst-case conditional value-at-risk as threshold point, and two of its nominal variants using value-at-risk and conditional value-at-risk as threshold points, respectively. We find that the proposed model under mixture distribution uncertainty exhibits a better performance over most of the data sets and scenarios than its CVaR-based robust counterpart. Under the box set, the proposed model performs similar or generates mixed results compared to its CVaR-based robust counterpart model. We also note that both the proposed robust models save investors against the risk of losses over the bearish phase of market in comparison to their nominal counterparts. Finally, on comparing the proposed model under mixture distribution uncertainty with the box uncertainty, the former model is found to be more suitable for optimistic investors, whereas the later strategy is more ideal for pessimistic investors.

Когда и почему региональные кластеры становятся базовым звеном современной экономики

In this paper, we examine the modern cluster theory and the specific features of regional innovation clusters as complex adaptive systems. Clusters have become a typical pattern of industrial organization in national economies under their transition to innovation-driven model of growth. We provide an overview of the contribution of various theoretical frameworks (evolutionary theory, spatial development theory, theory of technological change and system innovation, and Porter’s competitiveness theory) to the cluster concept and consider the latter from the perspective of complexity economics. On this basis, we differentiate true clusters from their nominal counterparts and propose three analytical dimensions to explore clusters, namely, as a special class of industrial agglomerations, as a special class of innovation ecosystems, and as a special class of economic projects (cluster initiatives). We examine the properties of clusters corresponding to each class and demonstrate their role in the geographical and functional fragmentation of production, in the integration of local exporters into global value chains, and in bridging communication gaps and developing collaboration among economic agents. We show that clusters occupy a central place among various types of business networks and have a comparative edge making them key building blocks of the modern industrial landscape. Further, we explain how the innovation capacity of clusters is affected by network synergy effects arising from the triple-helix pattern of collaboration among their participants. Finally, we draw conclusions regarding national cluster supporting policies, including those applied in modern Russia.

Iterative Learning Control of Iteration-Varying Systems via Robust Update Laws with Experimental Implementation

Iterative learning control (ILC) is an efficient way of improving the tracking performance of repetitive systems. While ILC can offer significant improvement to the transient response of complex dynamical systems, the fundamental assumption of iteration invariance of the process limits potential applications. Utilizing abstract Banach spaces as our problem setting, we develop a general approach that is applicable to the various frameworks encountered in ILC. Our main result is that robust invariant update laws lead to stable behavior in ILC systems, where iteration-varying systems converge to bounded neighborhoods of their nominal counterparts when uncertainties are bounded. Furthermore, if the uncertainties are convergent along the iteration axis, convergence to the nominal case can be guaranteed.

Intransitive psych verbs and nominalisation in Xitsonga

Although scholars generally agree that there are some similarities between verbs and their associative derived nominals, they are yet to find common ground as to the extent of the verbal properties that are shared by their nominal counterparts. In this article the extent of similarities between psych verbs and their associated derived nominals in Xitsonga were examined, while attention was paid to properties that are inherited by the derived nominals. The derived nominals that were examined were derived from intransitive verbs. Noun classes that allow nominalisations to occur more regularly and those that do not allow the regular occurrence of nominalisations were identified. The semantic structures of the derived nominals under investigation were analysed in terms of Pustejovsky's Generative Lexicon Theory (1995) of lexical semantic representation of nominals, which included these levels of meaning, namely the argument structure, the event structure and the qualia structure so as to establish whether they inherit the semantic features of their verbal counterparts. The idea of classifying nominals into stage-level nominals and individual-level nominals (Busa, 1996) were considered to see whether the same notion held for derived nominals from psych verbs in Xitsonga.

Partitive and pseudopartitive structures Partitive and pseudopartitive structures in temporal adverbials

The article discusses the interpretation and structure of those durative and frame adverbials in English which contain partitive or pseudopartitive constructions (e.g. for 18 months of my life and in 18 months of repairs ). In addition to the oft-discussed for and in -adverbials, the paper considers adverbials headed by through(out) and within as well. Building on the observation that these adverbials contain a measure phrase, an adverbial structure is proposed which parallels the structure of other measure phrase expressions. It is shown that some durative and frame adverbials have the expected partitive and pseudopartitive interpretation; this permits a treatment that relies on nominal counterparts such as 18 pounds of (the) sand , with a nominal projection serving as the (pseudo)partitive structure. However, some in -adverbials and all within -adverbials are interpreted differently. These adverbials have a boundary interpretation, which is shown in the example We knew within five minutes of talking to her / within five minutes of her arrival that her story was true . It is suggested that the boundary interpretation arises because the of -phrase is a PP, with a structure reminiscent of a locative PP rather than a nominal projection.

Adaptive Metric Learning Vector Quantization for Ordinal Classification

Many pattern analysis problems require classification of examples into naturally ordered classes. In such cases, nominal classification schemes will ignore the class order relationships, which can have a detrimental effect on classification accuracy. This article introduces two novel ordinal learning vector quantization (LVQ) schemes, with metric learning, specifically designed for classifying data items into ordered classes. In ordinal LVQ, unlike in nominal LVQ, the class order information is used during training in selecting the class prototypes to be adapted, as well as in determining the exact manner in which the prototypes get updated. Prototype-based models in general are more amenable to interpretations and can often be constructed at a smaller computational cost than alternative nonlinear classification models. Experiments demonstrate that the proposed ordinal LVQ formulations compare favorably with their nominal counterparts. Moreover, our methods achieve competitive performance against existing benchmark ordinal regression models.

A Fast Fault Detection Scheme for Power Converters In Distributed Generation Systems

In this paper, a fault detection algorithm based on voltage disturbances is proposed and analyzed. This method observes the voltage characteristics instead of the current amplitude, that is the most common approach in power distribution electrical systems. The proposed system uses a dual quadrature signal generator for each voltage component in a stationary reference frame to extract its positive- and negative-sequence components. Furthermore, a frequency-locked loop is used to estimate the voltage frequency. The voltage amplitude and frequency instantaneous values are compared with the nominal counterparts by means of hysteresis comparators. As a result, a fast and reliable fault detector system is obtained. Simulations and experimental results are presented to illustrate the feasibility and performance of the proposed scheme.

Afterword: Nominalizations in syntactic theory

This afterword constructs a working typology of nominalizations, based on but not restricted to the papers collected in this special issue. The typology is based on what we call the Functional Nominalization Thesis (FNT), a version of the model of “mixed projections” proposed in Borsley and Kornfilt (2000) which claims that nominal properties of a nominalization are contributed by a nominal functional projection; above that projection the structure has nominal properties, below it, verbal properties. We argue for four possible levels of nominalization, CP, TP, vP and VP. We show that certain internal syntactic phenomena are characteristic of different levels of nominalization: genitive subjects of nominalization at TP and below, genitive objects of nominalization at vP and below. We suggest that the inventory of categories implicated in nominalization is quite restricted: D, and nominal counterparts of ‘light’ verbal categories. We examine two alternatives to the FNT, the framework of Panagiotidis and Grohmann (2009) and Bresnan's (1997) head-sharing approach, and argue that our treatment is more appropriate under a minimalist approach, as it accommodates the facts within an independently motivated inventory of functional categories, without positing a special type of category limited only to nominalizations. We counter Bresnan's objections against a syntactic derivation of nominalizations by showing that a word's lexical integrity can be successfully violated by “suspended affixation” in syntactically derived nominalizations in Turkish while such integrity has to be respected in lexically derived nominalizations.

Reliability Based Design Recommendations for an Electromechanical Actuator Test Stand


 
 
 The quality and robustness of data sets of faulted electromechanical actuators (EMAs) are necessary to strengthen aircraft prognostic data analysis of such systems. Primary flight surface control actuators are of particular interest because the lack of known failure data erodes the confidence of the component and subsequently sub-system health predictions. To aid in this research, an EMA test stand has been designed and built to help in predicting the life and wear characteristics of faulted actuators with respect to their nominal counterparts. Faults are injected into the actuator during in-flight experiments while actuator parameters are recorded and then post-processed on the ground. This paper provides an assessment of the availability and reliability of the current EMA test stand design. Using the performance history of similar components in the field, this paper specifically demonstrates design aspects of the test stand that affect test system design and fault data quality. The study has been conducted to validate the test stand design, as well as offer design recommendations to increase test stand availability and ability to supply quality and robust fault to failure data sets.
 
 

Functional motivations in the development of nominal and verbal gerunds in Middle and Early Modern English

This article examines the use of three gerund constructions in Middle and Early Modern English on the basis of corpus data covering the period 1250–1640. The constructions examined are verbal gerunds (eating the apple), bare nominal gerunds (eating of the apple), and definite nominal gerunds (the eating of the apple). It is argued that the success of verbal gerunds in the history of English can only be understood against the background of the interaction with their nominal counterparts. An analysis is offered of how the system of gerund constructions is functionally organised, comparing discourse-functional behaviour, distribution, and internal syntax across the three gerund types. It is shown that verbal gerunds closely resemble bare nominal gerunds in terms of discourse-functional behaviour and distribution, but are syntactically more flexible. As a result, verbal gerunds could replace bare nominal gerunds, copying their function but adding syntactic flexibility. By contrast, definite nominal gerunds, being functionally distinct from the other two types, developed a number of specialised uses, which ensured their survival. These conclusions throw light on issues of functional motivation in the development of the English gerund. Historical change is seen to be grounded in synchronic functional organisation. At the same time, it is shown that the only existing explanation for the rise of verbal gerunds (attributing their success to their ability to combine with prepositions) can only be partly correct.

Trois petites études sur les prédicats de communication verbaux et nominaux

Three short studies on some verbal and nominal predicates of communication – We recall in this paper the fact that derivational properties are transformational properties as well. Hence the theoretical possibility of collecting some verbs, nouns, and adjectives into the same syntactico-semantic class of predicates. A few examples are provided of such “extended classes of predicates” : the predicates of congratulating and thanking, of manner of speaking, of predicting and of information following a demand. Thus the classification of the French verbs by Jean Dubois et Françoise Dubois-Charlier is confirmed by the properties of the possible nominal counterparts. Moreover, taking the noun properties into account brings in the fore certain syntactico-semantic subclasses the verbs themselves cannot reveal.

Why Japanese is different

A new theory of parametric variation is developed to explain certain differences between English and Japanese. Under a syntactic approach to derivational morphology, a fundamental hypothesis is proposed which states that Japanese is a ‘nominal language’, where all verbs are derived from nouns, and thus differs from English, where verbs and their nominal counterparts are derived from common roots in a parallel way. More specifically, it is argued that whereas in English verbs are derived by verbalization of simple roots, in Japanese they are derived by verbalization of nominalized roots. It is proposed that a parameter couched in terms of selectional relations between syntactic heads is responsible for the difference. It is shown that this parametric difference, coupled with syntactic principles, makes it follow that all Japanese nouns are non-θ-markers, which in turn explains unexpected properties related to the distribution of arguments in Japanese nominals. It is also shown that the proposed approach provides a simple account of the properties exhibited by lexical and null arguments in Japanese clauses that would otherwise remain mysterious.

Identification of rabbit immunoglobulin latent Cκ1 allotype genes alters the concept of allelic inheritance

In the rabbit, expression of immunoglobulin Cκ1 light chain genes is believed to be under allelic control. Conventionally, four nominal allotypic variants, b4, b5, b6 and b9 have been shown to be co-dominantly expressed at the Cκ1 gene locus. Analogously, the heavy chain allotypes, VHal, VHa2 and VHa3, found in the V region, are also believed to be inherited co-dominantly. However, after our earlier discovery of non-allelic or latent allotypes in the serum and on cell surfaces, we subsequently reported that cDNA sequences for latent b5 and b6 were identical to nominal b5 and b6, respectively (Ishaq et al., 1990). The latent b5 cDNAs were from two homozygous b4,b4 rabbits; the latent b6 cDNA was found in a heterozygous b4,b9 rabbit. The cDNA sequences had been obtained from lymph nodes and spleens of rabbits which had been infected with Trypanosoma brucei in order to induce latent allotypes more consistently. In this article, employing spleen DNA from three different T. brucei-infected rabbits, (one, heterozygous b4,b9; two others, homozygous, b4,b4), we initially detected two bands by Southern analysis after Hind III digestion using a 624 base pair Cκ1 b4 probe derived from a b4,b4 rabbit. However, the probe was non-specific allotypically as it hybridized to b5, b6 and b9 Cκ1 DNA. Therefore, in order to search for the latent genes, we used allotype-specific oligonucleotides for b5, b6 and b9 to probe DNAs from both normal and T. brucei-infected rabbits by Southern blotting. At the outset, employing a b4 oligonucleotide probe, we detected a single 5.8 Kb segment in two b4,b4 rabbit DNAs after Bgl II digestion. The findings, using the 624 base pair Cκ1 b4 probe and the b4 oligomer, agreed with earlier data reported by others. Subsequently, we tested kidney, liver and spleen DNAs from one of these and other rabbits for genomic latent b5, b6 and b9 using these specific oligomeric probes. For each latent allotype, Southern analysis revealed latent-allotype specific DNA segments in the genome. After cosmid cloning and sequencing, latent κ1, b5, b6 and b9 genes were found to be identical in their coding regions with their nominal counterparts. The genes contained at the 5′ end the PyPyXPyAG RNA splice acceptor site found in immunoglobulin and many eukaryotic genes, as well as the termination codon TAG, together with AATAAA and the T-rich sites responsible for cleavage-polyadenylation in the untranslated region downstream from the 3′ end. Single cosmid clones representing the b5, b6 and b9 genes were mapped for restriction sites which resulted in identifying putative Jκ and enhancer regions. The results thus indicate that latent allotype genes are potentially functional. The data provide evidence that allotypes are not strictly controlled by allelic genes but must be regulated by an hierarchical mechanism which provides for synthesis of allelic allotypes mainly (10–20 mg/ml) together with non-allelic allotypes at lower concentrations (2–20 μg/ml) following activation of the latent genes. These results lay to rest the belief that Cκ1 latent allotypes are the products of scrambled genes or idiotypic mimicry. Importantly, we now have the possibility of investigating the factors leading to latent allotype gene expression, the Vκ and Jκ regions associated with the genes, and therefore whether antibody diversity is expanded. We do not know, nor do we imply, that latent allotypes are present in all rabbits. However, since the four conventional Cκ1 allotypes are present in the genome of several of our tested rabbits, and are presumably functional, we are faced with the probability that rabbit allotypes under certain conditions may in fact behave as isotypes and not allotypes.

Cooperation in Health Affairs Between Adjacent International Communities: A Successful Model

The border between the United States and Mexico presents a number of problems related to health that are simultaneously local and international. Large-scale government-to-government interactions have generally failed to achieve lasting cooperation on important health issues, with a few important exceptions. One reason for this may be that the issues have been complicated by much larger and more complex social, cultural, economic, and political differences. Another is that large organizations must each function according to their own mandates, goals, and procedures and may not mesh well with others, even with nominal counterparts. In 1981 we conceptualized a model for encouraging binational cooperation on small-scale local projects. The model incorporates three elements: a significant and difficult but soluble technical problem affecting both sides of the border (the "technocratic factor"), a mutually respected individual or team whose function is to facilitate communication and prevent misunderstandings (the "human factor"), and the actions of governments or institutions larger than the working groups (the "institutional factor"). Subsequently, we applied the model to water quality and to the distribution of sources of toxic substances in the border area, which met the criteria for the technocratic factor. Two highly respected figures in environmental health, one American and one Mexican, mediated between colleagues on either side of the border and facilitated the development of projects. Finally, after the projects had been under way long enough to have demonstrated their viability and personal interactions among the principals had become trusting and collegial, the institutional factor was admitted and major financial and administrative support obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for linked expression of latent allotypes of the heavy chain constant and variable regions.

CH allotypes were determined for rabbit IgG and antibody molecules identified and isolated on the basis of their expression of latent group a (VH) allotypic determinants. Serologic and chemical typing of the purified molecules revealed that five out of 10 individual preparations studied expressed d allotypes not present in the rabbit as a nominal allotype. None of the latent VH-CH combinations represented products of a new or unusual arrangement of VH and CH structural genes. This result indicates that the molecules with latent allotypes express their VH and CH allotypes in the same combinations as do their nominal counterparts and do not result from misspairing of separate genes involved in H chain synthesis.

Real and Nominal Efficient Sets

incorporate the influence of inflation in constructing mean-variance efficient portfolios. He used two different sets of data in deriving the portfolio composition. One was the history of nominal returns of securities; the other was the history of real returns. The efficient portfolios derived from the real data differed in composition from their nominal counterparts and were found to dominate them. Solnik [7] has explored the impact of inflation on the composition of the efficient set. He shows that the real efficient set can be expressed as a combination of the real minimum variance portfolio and a second portfolio common to all investors. Although the second portfolio has no net investment (sum of portfolio investment proportions is zero), the amount of it that is held will vary depending on individual tastes. This paper extends the work of Solnik in that it investigates the difference between the real and nominal efficient sets by showing that every nominal efficient portfolio can be transformed into a real efficient portfolio by the additional purchase of a hedge portfolio. The hedge portfolio requires no net investment, has zero expected return, and its composition does not depend on the composition of the nominal efficient portfolio. The derivations and analysis of this hedge portfolio reveals several interesting facts: (1) If there exists one portfolio that is nominal efficient but not real efficient, then no portfolio can be efficient both in real and nominal terms. Similarly, if there exists one portfolio that is efficient both in nominal and real terms, then all efficient portfolios are both nominal efficient and real efficient; the nominal efficient set and the real efficient set are either identical or disjoint. (2) If the real and nominal efficient sets are identical and the market portfolio is efficient, the risk and expected return of any asset is determined by its covariance with the inflation rate. (3) If the real and nominal efficient sets are disjoint, the real variance of any nominal efficient portfolio can be reduced, with no additional net investment, by acquiring the hedge portfolio. The acquisition of the hedge portfolio will reduce the real variance by an amount equal to the covariance between the hedge portfolio and the inflation rate.