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The main reason for the low accuracy of magnetometer-based autonomous orbit determination is the coarse accuracy of the geomagnetic field model. Furthermore, the geomagnetic field model error increases obviously during geomagnetic storms, which can still further reduce the navigation accuracy. The purpose of this paper is to improve the accuracy of magnetometer-based autonomous orbit determination during geomagnetic storms.

In this paper, magnetometer-based autonomous orbit determination via a measurement differencing extended Kalman filter (MDEKF) is studied. The MDEKF algorithm can effectively remove the time-correlated portion of the measurement error and thus can evidently improve the accuracy of magnetometer-based autonomous orbit determination during geomagnetic storms. Real flight data from Swarm A are used to evaluate the performance of the MDEKF algorithm presented in this study. A performance comparison between the MDEKF algorithm and an extended Kalman filter (EKF) algorithm is investigated for different geomagnetic storms and sampling intervals.

The simulation results show that the MDEKF algorithm is superior to the EKF algorithm in terms of estimation accuracy and stability with a short sampling interval during geomagnetic storms. In addition, as the size of the geomagnetic storm increases, the advantages of the MDEKF algorithm over the EKF algorithm become more obvious.

The algorithm in this paper can improve the real-time accuracy of magnetometer-based autonomous orbit determination during geomagnetic storms with a low computational burden and is very suitable for low-orbit micro- and nano-satellites.

This paper's purpose was to examine the impact of geomagnetic activity (GMA) on the timing and valuation of earnings information disclosed by firms every quarter.

The authors start the analyses with a sample of 112,669 client firms from 1989 to 2018. To analyze the impact of GMA on the earnings response coefficient (ERC), the authors use the three-day cumulative abnormal returns and cumulative abnormal returns for the extended post-earnings announcement window [2, 75] as the dependent variables. The authors interact unexpected earnings (UE) with the C9 Index, an index commonly used to measure GMA and study how GMA affects the pricing of new public information. To examine the effect of GMA on the timing of disclosure of earnings news, the authors regress a variant of the GMA index on the propensity to disclose bad earnings news.

The authors find significantly lower earnings response coefficients during periods of high GMA. This effect is permanent and stock prices do not correctly incorporate the implications of earnings information over time. The authors also show that managerial behavior is affected by GMA as well and the managers are more (less) likely to release bad (good) news during periods of higher activity. Finally, the authors also find that in situations where stakeholders are likely to rely on modern technology that depends minimally on humans, the adverse impact of GMA on the pricing of earnings information is mitigated.

The literature on the effect of GMA on the capital market is very limited and focuses primarily on stock returns, while the behavioral finance literature focuses on circumstances like weather, temperature and sporting outcome to study how the investors' mood affects their capital market behavior. The authors add to both the literature by investigating how GMA influences investors' and managers' behaviors in the capital market.

The purpose of this paper is to design, build and test a low power high frequency (HF) transmitter that can be received by the Super Dual Auroral Radar Network (SuperDARN) radar installed at SANAE IV, the 4th South African National Antarctic Expedition Station. It is proposed that it may be possible to do propagation studies using the radar and the fixed frequency, ground-based HF transmitter beacon. Interpretation of the measurements can be used to study the ionosphere, especially Travelling Ionospheric Disturbances, which are signatures of atmospheric gravity waves.

In the absence of the actual deployment of the HF transmitter beacon in Antarctica, extensive simulations have been done to evaluate the expected performance of the transmitter in relation to the SuperDARN. A field trial has been executed between Hermanus (34.4241° S, 19.2247° E) and Pretoria (34.0558° S, 18.4589° E) in South Africa. In future, the beacon will be placed at the South Pole with its antenna radiating towards SANAE IV.

The HF transmitter conforms to the power and frequency stability requirements both during propagation tests conducted between Hermanus and Pretoria, as well as when the device was exposed to temperatures that ranged from +40°C to −45°C in a thermal chamber. Propagation in Antarctica is expected to differ from the field tests conducted due to the differences in density and dynamics of the polar ionosphere, compared to the mid-latitude ionosphere.

Space weather research, including forecasting atmospheric gravity waves and determining the expected electron density profile of the ionosphere, is of great scientific interest. The data received from the HF beacon can be used to study and characterize the ionosphere of the region between the South Pole and SANAE IV. Parameters of the ionosphere, such as electron density, geomagnetic storm effects, ionospheric motions and sky wave propagation paths will be better understood from analysing the signal received from this transmitter after it has been reflected and refracted by the ionosphere.

The purpose of this paper is to examine the effect of investors’ emotional state (mood) on their trading behaviour and performance.

A sample from a representative survey of 328 Greek individual investors has been used to empirically test the validity of the proposed associations. An iterative data collection process was followed, where individual investors had to complete a questionnaire every time they were trading in the Athens Stock Exchange, for a period of ten months. Exploratory factor analysis was first used to analyse the data set, followed by cluster analysis (to identify investor profiles based on differences in their mood).

Two clusters have been identified. The first cluster profile includes investors with high score of positive mood (thus, high energetic arousal and hedonic tone, low tense arousal and anger frustration), while the second profile consists of investors with negative mood (low energetic arousal and hedonic tone, high tense arousal and anger frustration). The comparison between the two profiles has shown that investors with positive mood achieve higher stock returns than investors with negative mood.

To the best of the authors’ knowledge there is no other similar study.

Historically, the study of the world’s economy was classified into Micro-economics and Macro-economics. Perhaps, contemporary economists should learn from the universe which we are part of. Let us name this as “Uni-economics.” Many scientists have found that sunspots affect human behavior. Some research findings even relate the 11-year periodic cycle to war and peace of mankind. It is also widely known in the medical profession that sunspot radiation actually affects our human body. With all these evidence in mind, the purpose of this paper is to investigate how sunspot activities can affect business growth since 1960s when the global economy was building up fast since the Second World War.

The econometrics methodology deployed is in three steps. First, time series techniques were deployed to track down the changes of Sunspot Counts over the last 48 years on the world’s four main financial indices, i.e., S & P, FTSE, Nikkei and HSI. Second, the long run function of a particular stock price index could be specified as a natural logarithm transformation function. Finally, Granger’s co-integration methodology is deployed to test the equilibrium relationships.

This paper has harnessed a set of system and process that can ensure the long-term productivity and business growth of firms in this contemporary business world. It is predicted with 80 percent confidence that the next property depression in some affluent cities will happen in 2014/2015, with the global financial tsunami coming in 2019.

More important is how organizations can make use of the trade-wind and avoid the counter-wind from the Uni-economics phenomena for their quality, productivity and business growth, in accordance to the Deming Cycle. As recalled from the previous two oil crisis (around 1975, 1986) and the two financial tsunami (1997 and 2008), 40-year-old organizations that can still survive today must have done something good, despite all these turmoil confronting them.

This paper sets out to detect and characterize electric fields in the ground (such as stray current fields) using a tandem time/frequency method of signal analysis.

Results were obtained from investigations performed in the presence of a generated electric field with controlled variable characteristics, and in the presence of an electric field generated by a tramline. The analysis of measurement registers was performed using Short‐Time Fourier Transformation. The results were presented in the form of spectrograms, which illustrate changes in the spectral power density of the measured signal versus time.

Tandem time/frequency analysis reveals the random or deterministic character of the electric field, enabling its complete time/frequency characteristics to be obtained. Such information is inaccessible using exclusively the frequency analysis methods that utilize classical Fourier transformations. Moreover, an analysis of the spectral power density distribution of the signals in three directions on the ground surface makes it possible to define the localization of the field source.

Analysis methods for electric fields in the ground should be adapted to the evaluation of non‐stationary signals because the stray currents are of this type. Such a possibility is given by combined analysis in the domains of time and frequency. This method can be used as complementary to applied measurement techniques of stray current interference.

The method of electric field detection and characterization, as related to stray currents, previously has not been presented in the literature. This method of signal analysis may be adopted for other investigations that are reliant on the registration of voltages or potentials characterized by arbitrary frequencies.

The continent of Antarctica consists of 14 million km², roughly equivalent to the whole of South America, and is of immense interest to humanity, in particular to the countries of the Antarctic Treaty. The Antarctic continent is the continent of superlatives: it is almost isolated from the rest of the continents, and is severely cold, windy, and dry. In winter, the Antarctic area increases to nearly 32 million km², because of formation of a 1,000km wide ice‐belt. The average depth of ice on the continent is in the order of 2,000m, and in the transantarctic region this depth is 4,800 meters. Antarctica is the biggest sweet water reservoir of the planet earth. Icebergs are common and huge ones (190km in length and 130km wide) have also been observed. The minimum temperature recorded (–89.2°C) at Vostok (Russian base) on 21 July 1983 is also the minimum recorded environmental temperature on the planet earth. Because of extreme temperature variations the Antarctic winds have high velocity. The environment is very dry and at the center of the continent the dryness is of the same magnitude as in the driest desert anywhere on the planet. This is the only uninhabited continent of the planet, except for some 50 research bases which cover an insignificant area located on the continent and the Antarctica Peninsula. Because of its economic, strategic, geopolitical, scientific, meteorological, and oceanographic importance and possible exploitation in the future, Antarctica has been attracting greater attention every day. Antarctica is basically concentrated around the South Pole and it touches the Atlantic, Pacific, and Indian Oceans. Brazil, in common with many other nations, has geopolitical interests and in untapped mineral deposits (considerable deposits of coal, petroleum, gas). In the south, where the Atlantic, Pacific and Indian Oceans meet, the cold water of Antarctica is the habitat housing hundreds of species of sea life. Unrestricted and unbalanced exploitation of Antarctica could cause changes in the meteorological and oceanographic balance. In the present paper, the Brazilian Antarctic Program, and summarized results of studies of Antarctic soil, rocks, and sediments are reported.

Two high‐powered satellites built by Hughes Space and Communications Company (HSC) will bring true direct broadcast satellite (DBS) service to homes throughout North America starting in early 1994.