Time-frequency representation of earthquake accelerograms and inelastic structural response records using the adaptive chirplet decomposition and empirical mode decomposition

In this paper, the adaptive chirplet decomposition combined with the Wigner-Ville transform and the empirical mode decomposition combined with the Hilbert transform are employed to process various non-stationary signals (strong ground motions and structural responses). The efficacy of these two adaptive techniques for capturing the temporal evolution of the frequency content of specific seismic signals is assessed. In this respect, two near-field and two far-field seismic accelerograms are analyzed. Further, a similar analysis is performed for records pertaining to the response of a 20-story steel frame benchmark building excited by one of the four accelerograms scaled by appropriate factors to simulate undamaged and severely damaged conditions for the structure. It is shown that the derived joint time–frequency representations of the response time histories capture quite effectively the influence of non-linearity on the variation of the effective natural frequencies of a structural system during the evolution of a seismic event; in this context, tracing the mean instantaneous frequency of records of critical structural responses is adopted. The study suggests, overall, that the aforementioned techniques are quite viable tools for detecting and monitoring damage to constructed facilities exposed to seismic excitations

Modelling and simulation of a stationary high-rise elevator system to predict the dynamic interactions between its components

In a high-rise elevator system lateral vibrations of the suspension and compensating ropes, coupled with vertical motions of the car and counterweight are induced by the building structure motions. When the frequency of the building coincides with the fundamental natural frequency of the ropes, large resonance whirling motions of the ropes result. This phenomenon leads to impacts of the ropes on the elevator walls, large displacements of the car and counterweight making the building and elevator system unsafe. This paper presents a comprehensive mathematical model of a high-rise elevator system taking into account the combined lateral stiffness of the roller guides and guide rails. The results and analysis presented in the paper demonstrate frequency curve veering phenomena and a wide range of resonances that occur in the system. A case study is presented when the car is parked at a landing level where the fundamental natural frequencies of the car, suspension and compensating rope system coincide with one of the natural frequencies of the high-rise building. The results show a range of nonlinear dynamic interactions between the components of the elevator system that play a significant role in the operation of the entire installation

The Japanese Character and its Peculiarity – A Study of Carl Peter Thunberg’s Travel Account

Japan, with its increasing isolation in the 1630s – cumulating in the ban of all foreigners apart from Chinese and Dutch traders and restricting Dutch traders to the small artificial island Deshima in 1641 – only few foreigners received permission to enter the country (Rietbergen, 2003, p. 170). Since their travels were based on monetary and rarely on scientific interests, only a small number of travel accounts about Japan were published in the seventeenth and eighteenth centuries (Rietbergen, 2004, p. 56). When the Swedish botanist Carl Peter Thunberg (1743-1828) published his Resa uti Europa, Africa, Asia, förrättad åren 1770 – 1779 from 1788 onwards, it were around fifty years that no new narratives on Japan had been published in Europe.Thus, it is of no surprise that his travel account was widely read in Europe. Thunberg’s work was translated once into English and Japanese, twice into French and twice into German (Screech, 2005, pp. 61-62). Despite aiming for a neutral report about the Japanese society, Thunberg provides a personal account about the Japanese that is remarkably positive and entails only few negative comments (e.g. too strict obedience to rules). This paper answers the question in how far and in what way Thunberg sets the Japanese culture and society apart from the European one. Moreover, possible reasons for this positive account are given. This chapter works with the English translation by Charles Hopton of 1793-95, which was reedited in 2005 by Timon Screech. The page numbers that are given in this chapter are derived from the 2005 edition. The German original translation by Kurt Sprengel from 1792 can be found in Maastricht Jesuit collection and is also referred to in this chapter

Catalog of 93 Nova Light Curves: Classification and Properties

We present a catalog of 93 very-well-observed nova light curves. The light curves were constructed from 229,796 individual measured magnitudes, with the median coverage extending to 8.0 mag below peak and 26% of the light curves following the eruption all the way to quiescence. Our time-binned light curves are presented in figures and as complete tabulations. We also calculate and tabulate many properties about the light curves, including peak magnitudes and dates, times to decline by 2, 3, 6, and 9 magnitudes from maximum, the time until the brightness returns to quiescence, the quiescent magnitude, power law indices of the decline rates throughout the eruption, the break times in this decline, plus many more properties specific to each nova class. We present a classification system for nova light curves based on the shape and the time to decline by 3 magnitudes from peak (t3). The designations are S for smooth light curves (38% of the novae), P for plateaus (21%), D for dust dips (18%), C for cusp-shaped secondary maxima (1%), O for quasi-sinusoidal oscillations superposed on an otherwise smooth decline (4%), F for flat-topped light curves (2%), and J for jitters or flares superposed on the decline (16%). Our classification consists of this single letter followed by the t3 value in parentheses; so for example V1500 Cyg is S(4), GK Per is O(13), DQ Her is D(100), and U Sco is P(3).Comment: Astronomical Journal, in press, 19 figures, 73 page

The Societal Legacy of War: The Lasting Impact of War on Individual Attitudes in Post-War Society

Despite the substantial transformative impact wars have on people’s lives, the social and institutional consequences of war remain the least understood. This dissertation adds to a sparse, but growing body of literature on the micro-level consequences of war and advances our understanding of its societal legacy by analyzing how war influences individual attitudes in post-war societies. It contributes to the study of peace and conflict by drawing attention to the micro level and exploring how both interstate and internal wars may shape individual attitudes relevant for building long-lasting peace. Further, it expands the general literature on political science on the determinants of social and political attitudes and behavior by exploring the hitherto largely ignored impact of war on such attitudes. The impact of war on individual attitudes is analyzed empirically in three chapters. Chapter 2 (co-authored with Markus Freitag) scrutinizes the impact of individual and contextual war exposure on social trust in post-war Kosovo. Drawing from the psychological literature on war-related distress and posttraumatic growth, this study is motivated by the question whether the consequences of war for social attitudes always are negative, or whether war also can contribute to growth in social trust. Combining both individual and municipal data on war exposure in a multilevel framework, it further explores which of these types of war exposure have the strongest impact on individual attitudes. The findings of this chapter indicate that individual war experience has had a consistent, negative impact on social trust more than 10 years after the end of the war. The effect of municipal war exposure is not robust and is sensitive to the exclusion of specific municipalities. The second study in Chapter 3 takes a step back and examines the long-term impact of war exposure by studying the role that experiences during World War II have on people’s level of satisfaction with life in a comparative study of 34 countries. Motivated by the findings from related academic disciplines on the intergenerational transmission of the consequences of trauma exposure, this chapter not only scrutinizes the effect of war on directly affected individuals but also analyzes how family members’ experiences with war affect the well-being of members of the subsequent generations. The empirical findings are twofold. First, injury to oneself or injury or death of parents or grandparents has a lasting negative influence on individuals’ level of life satisfaction more than sixty years after the end of the war. This effect is remarkably robust and suggests that war experiences or their consequences become transmitted to subsequent generations. Second, the effect of war experiences is stronger for older respondents. Individuals reporting experiences from World War II are thereby less likely to experience the general upward trend in life satisfaction with age. Trying to understand the possible mechanisms through which the transmission of war experiences takes place, the study finds that war exposure is significantly related to lower self-reported health and a lower paternal level of education among relevant age cohorts. Finally, Chapter 4 (co-authored with Carolin Rapp) analyzes in detail how war affects political tolerance of the Sinhalese and Tamil populations toward each in post-war Sri Lanka. Using unique, all-island survey data collected after the 26-year-long civil war the chapter devotes special attention to the mechanism that may drive the relationship between war and individual attitudes. With structural equation modeling techniques, the chapter closely studies the role played by intergroup forgiveness and ethnic prejudice in the relationship between war experience and granting civil liberties. The analyses reveal that the likelihood to grant civil liberties in both ethnic groups depends on the civil liberty in question. Whereas a majority from both ethnic groups are willing to grant the right to vote, hold a speech, and to hold a government position, the right to demonstrate is highly contested and is only granted to the other group by very low shares of both ethnic groups. Further, the empirical findings show that the direct impact of war experience is less powerful than expected and, again, depends on the right in question. Instead, not being willing to forgive the other group, driven by war experience and ethnic prejudice, is a more consistent predictor of intolerance. These studies together imply that wars may have lasting, negative societal consequences. The effect may stretch across generations and have important implications for post-war peacebuilding and recovery policies. The finding that the impact of war on individual attitudes is not necessarily a direct result of war exposure but is driven by psychological responses to such events, in this case, the willingness to forgive, suggests that there are ways in which societies can promote positive social attitudes by focusing on the mechanisms at work. Further research on the mechanisms at work is needed to develop the most efficient policies for peaceful intergroup relations and thereby lasting peace

Mechanistic differences in interactions of HIV-1 and HIV-2 with dendritic cells

Pathogenic mechanisms that account for the dramatic differences between the HIV-1 and HIV-2 epidemics remain unknown. Myeloid dendritic cells (DCs) are sentinels of the immune system, which sense invading pathogens and initiate immune responses. I hypothesize that failure of HIV-2 to overcome DC-intrinsic defense mechanisms results in diminished virus replication and reduced pathogenesis in vivo. Recent studies from our laboratory have identified capture of HIV-1 by CD169 (Siglec1), which results in preservation of virus infectivity in peripheral non-lysosomal compartments and transfer to CD4+ T cells, a mechanism of DC-mediated trans infection. HIV-1 interaction with CD169 was dependent on incorporation of a ganglioside, GM3, in the virus particle membrane. We hypothesized that reduced interaction of HIV-2 with CD169 is crucial for its attenuated pathogenic phenotype in vivo. Interestingly, HIV-2 virion assembly sites were divergent from HIV-1, which correlated with reduced incorporation of GM3 in HIV-2 virions, and a significant decrease in capture of HIV-2 compared to HIV-1 by mature DCs. Furthermore, reduced CD169-dependent HIV-2 capture by DCs attenuated access of HIV-2 to DC-mediated trans infection. In contrast to the trans infection pathway, HIV-2 could establish productive infection in DCs, though productive infection of DCs by HIV-2 resulted in innate immune activation, induction of IFN-α production and attenuated spread of virus in DC – CD4+ T cell co-cultures. As opposed to HIV-2, productive infection of DCs by HIV-1 was attenuated and failed to trigger type I IFN responses, thus allowing for efficient spread of HIV-1 in DC – CD4+ T cell co-cultures. These results suggest that immune sensing of HIV-2 in productively infected DCs limits viral spread. Finally, we investigated GM3-expressing nanoparticles (GM3-NPs) for delivery of therapeutics that trigger innate immune responses in CD169+ myeloid cells as a novel strategy to mimic myeloid cell-intrinsic virus control observed in HIV-2 infection. We tested the ability of GM3-coated nanoparticles that incorporated a TLR2 ligand, Pam3CSK4, to activate CD169+ cells. Interestingly, Pam3CSK4 containing GM3-NPs robustly activated CD169+ cells. These results suggest that induction of dendritic cell-intrinsic type I IFN responses might be a fruitful therapeutic strategy to restrict HIV-1 replication in vivo

The Pimsletter on Business Strategy. Unions and Profits, 1978

Statistical analysis of return on investment and productivity in a union environment

Predicting Prices Of S&P 500 Index Using Classical Methods and Recurrent Neural Networks

This study implements algorithmic investment strategies based on classical methods and a recurrent neural network model. The research compares the performance of investment algorithms on time series of the S&P 500 Index covering 20 years of data from 2000 to 2020. We present an approach for the dynamic optimization of parameters during the backtesting process by using a rolling training-testing window. Each method was tested in terms of robustness to changes in parameters and evaluated by appropriate performance statistics, such as the Information Ratio and Maximum Drawdown. The combination of signals from different methods was stable and outperformed the benchmark of the Buy&Hold strategy, doubling its returns while maintaining the same level of risk. Detailed sensitivity analysis revealed that classical methods utilizing a rolling training-testing window were significantly more robust to changes in parameters than the LSTM model

Using the signal-to-noise ratio of GPS records to detect motion of structures

Although major breakthroughs have been achieved during the last decades in the use of Global Positioning System (GPS) technology on structural health monitoring, the mitigation of the biases and errors impeding its positioning accuracy remains a challenge. This paper tests an alternative approach that can increase the reliability of the GPS system in structural monitoring by using the spectral content of the signal-to-noise ratio (SNR) of GPS signals to detect frequencies of antenna vibrations. This approach suggests the potential of using SNR data analysis as a supplement to low-quality positioning solution or as a near real-time alert of excessive vibration proceeding the position solution calculation. Experiments, involving a GPS antenna subjected to vertical vibrations of 0.4- to 4.5-cm amplitude at a range of frequencies between 0.007 and 1 Hz, examine the dynamic multipath-induced SNR response corresponding to the antenna motion. Synchronised fluctuations in the SNR time series were observed to reflect the antenna motion and their spectral content to include the frequencies of motion. SNR records from the GPS monitoring of the Wilford suspension bridge were used to validate the SNR sensitivity to controlled vibrations of the bridge deck. The natural frequency of 1.64 Hz was extracted from SNR measurements using spectral analysis on a 6-mm amplitude vibration, and the frequency of the semistatic displacement (∼0.02 Hz) was revealed in the SNR records permitting, after appropriate filtering, the estimation of a few millimetre semistatic displacement from the GPS time series without the need for any other sensor

The influence of lead on concentrates quality produced in KGHM Polska Miedz concentrator plants

The behaviour of lead compounds present in feed of beneficiation process has been discussed. Changeability of copper and lead content in feed during last decades has been described. Galena was pointed as a major source of lead and the beneficiation kinetic of this mineral was presented comparing with other sulphides, including copper sulphides. Significant amount of galena together with its very good concentrating properties crucially effect on quality of concentrates produced in Lubin concentrator plant