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The empirical examples of the green-beard genes, once a conundrum of evolutionary biology, are accumulating, while theoretical analyses of this topic are occasional compared to those concerning (narrow-sense) kin selection. In particular, the recognition error of the green-beard effect that the cooperator fails to accurately recognize the other cooperators or defectors is readily found in numerous green-beard genes. To our knowledge, however, no model up to date has taken that effect into account. In this article, we investigated the effect of recognition error on the fitness of the green-beard gene. By employing theories of evolutionary games, our mathematical model predicts that the fitness of the green-beard gene is frequency dependent (frequency of the green-beard gene), which was corroborated by experiments performed with yeast FLO1. The experiment also shows that the cells with the green-beard gene (FLO1) are sturdier under severe stress. We conclude that the low recognition error among the cooperators, the higher reward of cooperation, and the higher cost of defection confer an advantage to the green-beard gene under certain conditions, confirmed by numerical simulation as well. Interestingly, we expect that the recognition error to the defectors may promote the cooperator fitness if the cooperator frequency is low and mutual defection is detrimental. Our ternary approach of mathematical analysis, experiments, and simulation lays the groundwork of the standard model for the green-beard gene that can be generalized to other species.

In a diverse population, where many species are present, competitors can fight for surviving at individual and collective levels. In particular, species, which would beat each other individually, may form a specific alliance that ensures them stable coexistence against the invasion of an external species. Our principal goal is to identify those general features of a formation which determine its vitality. Therefore, we here study a traditional Lotka-Volterra model of eight-species where two four-species cycles can fight for space. Beside these formations, there are other solutions which may emerge when invasion rates are varied. The complete range of parameters is explored and we find that in most of the cases those alliances prevail which are formed by equally strong members. Interestingly, there are regions where the symmetry is broken and the system is dominated by a solution formed by seven species. Our work also highlights that serious finite-size effects may emerge which prevent observing the valid solution in a small system., Comment: 10 double-column pages, 11 figures

We investigate evolving dynamics of cyclically competing species on spatially extended systems with considering a specific region, which is called the “wildlife refuge,” one of the institutional ways to preserve species biodiversity. Through Monte-Carlo simulations, we found that the refuge can play not groundbreaking but an important role in species survival. Species coexistence is maintained at a moderate mobility regime, which traditionally leads to the collapse of coexistence, and eventually, the extinction is postponed depending on the competition rate rather than the portion of the refuge. Incorporating the extinction probability and Fourier transform supported our results in both stochastic and analogous ways. Our findings may provide valuable evidence to assist fields of ecological/biological sciences in understanding the presence and construction of refuges for wildlife with associated effects on species biodiversity.

Securing space for species breeding is important in the evolution and maintenance of life in ecological sciences, and an increase in the number of competing species may cause frequent competition and conflict among the population in securing such spaces in a given area. In particular, for cyclically competing species, which can be described by the metaphor of rock–paper–scissors game, most of the previous works in microscopic frameworks have been studied with the initially given three species without any formation of additional competing species, and the phase transition of biodiversity via mobility from coexistence to extinction has never been changed by a change of spatial scale. In this regard, we investigate the relationship between spatial scales and species coexistence in the spatial cyclic game by considering the emergence of a new competing group by mutation. For different spatial scales, our computations reveal that coexistence can be more sensitive to spatial scales and may require larger spaces for frequencies of interactions. By exploiting the calculation of the coexistence probability from Monte-Carlo simulations, we obtain that certain interaction ranges for coexistence can be affected by both spatial scales and mobility, and spatial patterns for coexistence can appear in different ways. Since the issue of spatial scale is important for species survival as competing populations increase, we expect our results to have broad applications in the fields of social and ecological sciences.

Asymmetrical rock-paper-scissors (RPS) competition has been perceived as a crucial factor in shaping species biodiversity, and understanding this ecological issue in a multi-species paradigm is rather difficult because community dynamics usually depend on distinct factors such as abiotic environments, biotic interactions and symmetry-breaking phenomenon. To address this problem, we employ a Lotka-Volterra competitive system consisting of both symmetrical, asymmetrical interactions and abiotic environment components. We discover that that asymmetrical RPS competition in heterogeneous environments can yield much richer dynamical behaviors, compared to the symmetrical and asymmetrical competition in homogeneous environments. While it is observed that species coexistence outcomes and/or oscillatory solutions are maintained as in the case of homogeneous environments, the nonuniformity in the environmental carrying capacities may lead to extra dynamics with regards to the appearance of survival states; for instance, coexistence of any two-species and single-species persistence states, which are not evident in the previous modelling studies. By means of bifurcation analysis, various salient features of the dynamical systems, including the emergence of certain attractors (e.g., different steady states, stable limit cycles and heteroclinic cycles) and co-dimension one bifurcations (e.g., transcritical and supercritical Hopf bifurcations) are realized in this ecological model. Overall, this modelling work provides a novel attempt to simultaneously encompass not only symmetry-breaking phenomenon through RPS competition, but also heterogeneity in the environments. This framework can provide additional insights to better understand various mechanisms underlying the effects of distinct ecological processes on multi-species communities.

Multistability is common feature resulting in nonlinear dynamical systems, and its characteristic can be generally depicted by investigating basin structures of initial conditions for give parameter settings. In this paper, we explore the formation of extinction states according to the change of strength of competition levels in the toy model for three species. Through the linear stability analysis, we find that the extinction state can be stable which is persistent. For specific conditions between intensities of two different competitions, we also found that the extinction state can be either bistable or tristable. In each case, the final state of the system can be characterized sensitively depending on initial conditions. To validate our results, we investigate basin structures of parameters for interspecific competition associated to a strength of intraspecific competition. In addition, we found that coexistence becomes robust as intraspecific competition is intensified relatively to the interspecific competition level. We hope our results can be a chance to suggest the emergence of the multistability according to complex competition structures on systems of many populations.

Interpatch migration between two environments is generally considered as a spatial concept and can affect species biodiversity in each patch by inducing flux of population such as inflow and outflow quantities of species. In this paper, we explore the effect of interpatch migration, which can be generally considered as a spatial concept and may affect species biodiversity between two different patches in the perspective of the macroscopic level by exploiting the coupling of two systems, where each patch is occupied by cyclically competing three species who can stably coexist by exhibiting periodic orbits. For two simple scenarios of interpatch migration either single or all species migration, we found that two systems with independently stable coexisting species in each patch are eventually synchronized, and oscillatory behaviors of species densities in two patches become identical, i.e., the synchronized coexistence emerges. In addition, we find that, whether single or all species interpatch migration occurs, the waiting time for the synchronization is exponentially decreasing as the coupling strength is intensified. Our findings suggest that the synchronized behavior of species as a result of migration between different patches can be easily predicted by the coupling of systems and additional information such as waiting times and sensitivity of initial densities.

This paper examines how proximity to an ethanol plant influences land-use and crop choice among producers. We estimated a Tobit model of crop choice within parcels located in Central Nebraska in a 2014 sample period in order to analyze changes in land-use and crop choice. We employed Geographic Information System (GIS) databases to access relevant data on crop choice and other land uses in the study area parcels, in addition to detailed information on the location and capacity of irrigation wells. We utilized an instrumental variable approach to account for the endogeneity of crop choice with ethanol refinery locations in the study area. Our regional model also took into account specific characteristics of the local processing markets for grains, including animal food manufacturers and livestock as well as ethanol plants. Our estimates revealed that ethanol plants alter land-use in several ways. We found that proximity to an ethanol plant increases the share of land allocated to corn cultivation up to a distance of 30 miles and that the portion of land parcels allocated to corn production falls with distance from an ethanol plant in a non-linear pattern. We also find that land allocation to grassland and pasture rises with distance from ethanol plants.

This study describes the theoretical performance of a successive interference cancellation (IC) technique as an electronic counter countermeasure and verifies its feasibility through experiments. In a radio navigation system using direct sequence/code division multiple access, strong pseudorandom signals can be used as interference sources for unauthorised users when regional radio navigation needs to be denied in a specific area, while authorised users can use both the strong signal and the global navigation satellite system (GNSS) ranging signal for navigation through the IC method. To determine the feasibility of this selective jamming concept, this study investigated its theoretical performance and compared the results with experimental ones. The experimental results show that a maximum jamming-to-signal ratio performance of 57 dB or higher can be achieved, which is similar to the theoretical estimation.

One of the common assumptions in previous spatial dynamics of cyclic competition is that, regardless of competing structure and strength among species, the spatial size of a network is considered as large as possible to avoid finite size effect for species biodiversity. In real ecosystems, however, species richness, which can be defined by spatial size and competition strength, can sensitively affect species coexistence as a competition among individuals becomes complicated. In this paper, we investigate the structural stability of coexistence of mobile species in three cyclic competition games due to network complexity in which imposes a size of a square lattice and competition strength among species. By exploiting the coexistence probability, our computations quantitatively reveal that the network complexity due to changes in the competition rate and lattice size can strongly affect the structural stability of coexistence in each model. In particular, intense intraspecific competition can yield the robust coexistence at small-sized lattices regardless of mobility, and strengthening interspecific competition simultaneously induces changes in critical mobility that hampers coexistence and in spatial size for stable coexistence. Qualitatively, we find that such structural stability of coexistence relates to the degree of stability of fixed points in deterministic systems. Our finding can be useful to gain insights into species coexistence on spatially extended systems with respect to network complexity.

Classic frameworks of rock-paper-scissors game have been assumed in a closed community that a density of each group is only affected by internal factors such as competition interplay among groups and reproduction itself. In real systems in ecological and social sciences, however, the survival and a change of a density of a group can be also affected by various external factors. One of common features in real population systems in ecological and social sciences is population flow that is characterized by population inflow and outflow in a group or a society, which has been usually overlooked in previous works on models of rock-paper-scissors game. In this paper, we suggest the rock-paper-scissors system by implementing population flow and investigate its effect on biodiversity. For two scenarios of either balanced or imbalanced population flow, we found that the population flow can strongly affect group diversity by exhibiting rich phenomena. In particular, while the balanced flow can only lead the persistent coexistence of all groups which accompanies a phase transition through supercritical Hopf bifurcation on different carrying simplices, the imbalanced flow strongly facilitates rich dynamics such as alternative stable survival states by exhibiting various group survival states and multistability of sole group survivals by showing not fully covered but spirally entangled basins of initial densities due to local stabilities of associated fixed points. In addition, we found that, the system can exhibit oscillatory dynamics for coexistence by relativistic interplay of population flows which can capture the robustness of the coexistence state. Applying population flow in the rock-paper-scissors system can ultimately change a community paradigm from closed to open one, and our foundation can eventually reveal that population flow can be also a significant factor on a group density which is independent to fundamental interactions among groups.

This study verifies the performance of the ionosphere-free L1 pseudorange for dual-frequency space-based augmentation systems (SBAS) users by both of theoretical analysis and experiments with actual GPS data. Although the dual-frequency pseudorange from ionosphere-free linear combinations is commonly used as a standard method, the ionosphere-free L1 range based on the weighted Hatch filter has advantages in terms of the amplification factor caused by a dual-frequency combination and filter weights optimised by the least-squares method. For the experimental analysis, RINEX data were collected from five National Geographic Information Institute reference stations on the Korean peninsula and used to generate an SBAS correction message following international SBAS specifications. The experimental results show that using the proposed method results in a 29% improvement in the range domain compared with the use of a traditional ionosphere-free linear combination filter. In the position domain, the proposed method shows a horizontal accuracy improvement of 16% after the application of post-processed SBAS orbit/clock corrections w.r.t. the traditional filter. Finally, this study also demonstrates that the accuracy of dual-frequency users can surpass than that of single-frequency SBAS users only if corrections are estimated with ionospheric delay-free measurements in the master station as well.

Cyclically competition models have been successful to gain an insight of biodiversity mechanism in ecosystems. There are, however, still limitations to elucidate complex phenomena arising in real competition. In this paper, we report that a multistability occurs in a simple rock-paper-scissor cyclically competition model by assuming that intraspecific competition depends on the logistic growth of each species density. This complex stability is absent in any cyclically competition model, and we investigate how the proposed intraspecific competition affects biodiversity in the existing society of three species through macroscopic and microscopic approaches. When the system is multistable, we show basins of the asymptotically stable heteroclinic cycle and stable attractors to demonstrate how the survival state is determined by initial densities of three species. Also, we find that the multistability is associated with a subcritical Hopf bifurcation. This surprising finding will give an opportunity to interpret rich dynamical phenomena in ecosystems which may occur in cyclic competition systems with different types of interactions.

Since Google launched the Android N in 2016, more than 30 brand new Android devices are providing user-domain with GNSS raw measurements, which are pseudorange, carrier phase and doppler observables. Before the Android N there was no other way to improve the position accuracy of the smart phone or tablet than A-GPS or DGPS-CP, which were only available at server-side or under a constraint of satellite visibility. Even though there is not yet any GNSS augmentation functionality implemented to feed the correction to the chipset, the access to the raw measurements allow users to improve the position accuracy of the devices and to applies them to various areas as desired. There are typical ways to correct the device pseudorange-based position such as DGNSS (Differential GNSS), PPP (Precise Point Positioning), SBAS (Satellite Based Augmentation System) and so on. In the case of DGNSS, DGNSS reference stations broadcast the PRC (Pseudo Range Correction) whose service area is 150km to 200km from each station, thus the user should include a function of selecting the reference station according to the user’s location. PPP is another augmentation solution which provides a global precise positioning service that uses detailed physical models and corrections, and precise GNSS orbit and clock products. One of the many advantages of PPP is that the PPP solutions of GNSS orbit and clock products are global. Currently, the IGS (International GNSS Service) provides users with the RTS products which consist of GNSS satellite orbit and clock corrections to the broadcast ephemeris in real time, whose data rate in IGS RTS (Real Time Service) product stream is about 2,000bps. SBAS is also a powerful enhancement to augment GPS by broadcasting augmentation messages including differential corrections and integrity information with a very low data rate of 250bps from a GEO satellite. Unlike DGNSS, all the users in the SBAS service area receive the same correction and information, so the user app does not need any model for selecting the reference station. Moreover, the data bandwidth is only 250 bps, which is about 10% of the PPP service, thus the users does not need to feel burdened by the cost of mobile data communication even though current GNSS module in Android device should receive the SBAS message on the internet, not on the L1 signal. Despite of the simplicity at the user side and the low data rate for the correction message, current SBAS system cannot fully utilize the multi-constellation effect of the Android devices. All the current SBAS systems except of the SDCM of Russia provide GPS-only augmentation messages, thus when Android smart devices supporting multi-constellations(GPS, GLONASS, Galileo, etc.) cannot utilize the advantages(i.e. improving the accuracy) of multi-constellations when applying the current SBAS message. To complement this disadvantage, we propose the L1 SFMC (Single-Frequency, Multi-Constellation) SBAS in this paper. The L1 SFMC SBAS method and its message protocols were the method suggested at ION GNSS+ 2017 to improve the performance of the L1 single frequency GNSS by containing all the information for the multi-constellation GNSS in the modified SBAS message format. We propose to remove the fast corrections and to assign additional time slots for providing the long-term corrections of GLONASS and other constellations. To include our suggested L1 SFMC SBAS in the suggested message format, we generated the long-term corrections using the precise orbit and clock products from the IGS Data Center. Also, we generated the ionospheric corrections for all the constellation using IGP(Ionospheric Grid Point) vertical delay estimates which has already been included in SBAS Message Type 26 and IONEX data. We carried out some experiments to confirm the effect of our suggested L1 SFMC SBAS corrections on Android smart device at Seoul, Korea. As a result of applying the L1 SFMC SBAS corrections to Android GNSS raw measurements on Samsung Galaxy S8 with 250bps, the mean values have been reduced from 2.02m(horizontal) and 9.49m(vertical) to 0.36m and 0.49m, and the RMS errors have been reduced from 5.19m(horizontal) and 10.56m(vertical) to 1.30m and 2.06m.

Dilution of Precision (DOP) is used as a parameter representing the geometrical position of visible satellites, and as a measure of position error of Global Navigation Satellite Systems (GNSSs). In previous studies, the Weight DOP (WDOP) was proposed by setting different weights based on the signal quality of the GPS satellite, and the signal quality of satellites was evaluated based on the elevation angle. In this study, Multi-Constellation Weighted DOP (MWDOP) is defined by expanding the weight matrix of GPS to the global navigation satellite systems (GPS, GLONASS, Galileo, and Beidou). The weight matrix is defined through actual data considering the elevation angle and pseudorange for each satellite system. Furthermore, the satellite selection algorithm is set up through sensitivity, which is calculated by dividing the difference between the DOP calculated for the entire set of satellites and the DOP calculated for a set excluding specific satellites divided by the DOP calculated for the entire set of satellites. If the calculated sensitivity is large, the excluded satellites are considered to have a large effect on the satellite positioning. This study provides more reliable criteria for selecting satellites by comparing DOP sensitivity and MWDOP sensitivity.

Understanding mechanisms which promote or hinder existing ecosystems are important issues in ecological sciences. In addition to fundamental interactions such as competition and migration among native species, existing ecosystems can be easily disturbed by external factors, and the emergence of new species may be an example in such cases. The new species which does not exist in a current ecosystem can be regarded as either alien species entered from outside or mutant species born by mutation in existing normal species. Recently, as existing ecosystems are getting influenced by various physical/chemical external factors, mutation due to anthropogenic and environmental factors can occur more frequently and is thus attracting much attention for the maintenance of ecosystems. In this paper, we consider emergences of mutant species among self-competing three species in the cyclic dominance. By defining mutation as the birth of mutant species, we investigate how mutant species can affect biodiversity in the existing ecosystem. Through microscopic and macroscopic approaches, we have found that the society of existing normal species can be disturbed by mutant species either the society is maintained accompanying with the coexistence of all species or jeopardized by occupying of mutant species. Due to the birth of mutant species, the existing society may be more complex by constituting two different groups of normal and mutant species, and our results can be contributed to analyze complex ecosystems of many species. We hope our findings may propose a new insight on mutation in cyclic competition systems of many species.

Tropospheric delay is one of the largest error source in pseudolite navigation system. Because a pseudolite is installed on the ground and transmits its signal to a user in the air or on the ground, the conventional tropospheric delay model developed for a satellite navigation doesn't work properly. In this paper, performance analysis of several pseudolite tropospheric delay models has been done using meteorological data. Based on the result, a new compensation method for Hopfield model has been proposed.

The characteristics of the SBAS satellite orbit and clock corrections are highly affected by the narrow network size in the Korean peninsula, which is expected to have an important role in the future dual frequency SBAS. The correlation between satellite corrections can be analyzed in terms of the spatial decorrelation effect which should be analyzed to keep the service area as wide as possible. In this paper, the characteristics of satellite error corrections for the potential Korean dual frequency SBAS were analyzed, and an optimal filter design approach is proposed to maximize the service area.

Global navigation satellite systems (GNSS) is operating widely in civil and military area. GNSS signals, however, can be easily interfered because its signal is vulnerable to jamming. Thus, a sort of backup or alternative system is needed in order that the navigation performance is assured to a certain degree in case of GNSS jamming. In order to suggest a series of backup or alternative system of regional navigation, in this paper, we introduced a high altitude long endurance unmanned aerial vehicle (HALE UAV) with pseudolites using inverted GPS and transceiver system. We simulated the positioning error of the regional navigation system using HALE UAV with inverted GPS or transceivers concepts. We estimated the position error of HALE UAV calculate user position errors based on the position error of HALE UAV and general pseudorange error.

The Ground-based Radio Navigation System (GRNS) is an alternative/backup navigation system based on time synchronized pseudolites. It has been studied for some years due to the potential vulnerability issue of satellite navigation systems (e.g., GPS or Galileo). In the framework of our study, a periodic pulsed sequence was used instead of the randomized pulse sequence recommended as the RTCM (radio technical commission for maritime services) SC (special committee)-104 pseudolite signal, as a randomized pulse sequence with a long dwell time is not suitable for applications requiring high dynamics. This paper introduces a mathematical model of the post-correlation output in a navigation sensor, showing that the aliasing caused by the additional frequency term of a periodic pulsed signal leads to a false lock (i.e., Doppler frequency bias) during the signal acquisition process or in the carrier tracking loop of the navigation sensor. We suggest algorithms to resolve the frequency false lock issue in this paper, relying on the use of a multi-correlator. A flight test with an unmanned helicopter was conducted to verify the implemented navigation sensor. The results of this analysis show that there were no false locks during the flight test and that outliers stem from bad dilution of precision (DOP) or fluctuations in the received signal quality.

In the case of satellite navigation positioning, the shielding of satellite signals is determined by the environment of the region at which a user is located, and the navigation performance is determined accordingly. The accuracy of user position determination varies depending on the dilution of precision (DOP) which is a measuring index for the geometric characteristics of visible satellites; and if the minimum visible satellites are not secured, position determination is impossible. Currently, the GLObal NAvigation Satellite system (GLONASS) of Russia is used to supplement the navigation performance of the Global Positioning System (GPS) in regions where GPS cannot be used. In addition, the European Satellite Navigation System (Galileo) of the European Union, the Chinese Satellite Navigation System (BeiDou) of China, the Quasi-Zenith Satellite System (QZSS) of Japan, and the Indian Regional Navigation Satellite System (IRNSS) of India are aimed to achieve the full operational capability (FOC) operation of the navigation system. Thus, the number of satellites available for navigation would rapidly increase, particularly in the Asian region; and when integrated navigation is performed, the improvement of navigation performance is expected to be much larger than that in other regions. To secure a stable and prompt position solution, GPSGLONASS integrated navigation is generally performed at present. However, as available satellite navigation systems have been diversified, finding the minimum satellite constellation combination to obtain the best navigation performance has recently become an issue. For this purpose, it is necessary to examine and predict the navigation performance that could be obtained by the addition of the third satellite navigation system in addition to GPS-GLONASS. In this study, the current status of the integrated navigation performance for various satellite constellation combinations was analyzed based on 2014, and the navigation performance in 2020 was predicted based on the FOC plan of the satellite navigation system for each country. For this prediction, the orbital elements and nominal almanac data of satellite navigation systems that can be observed in the Korean Peninsula were organized, and the minimum elevation angle expecting signal shielding was established based on Matlab and the performance was predicted in terms of DOP. In the case of integrated navigation, a time offset determination algorithm needs to be considered in order to estimate the clock error between navigation systems, and it was analyzed using two kinds of methods: a satellite navigation message based estimation method and a receiver based method where a user directly performs estimation. This simulation is expected to be used as an index for the establishment of the minimum satellite constellation for obtaining the best navigation performance.

All the current SBAS systems broadcast the augmentation message based on the L1-only SBAS MOPS (Minimum Operational Performance Standards), which is described in the RTCA DO-229 as an international standard. The L1 SBAS message was originally designed to support multi-GNSS constellations, but all the SBAS systems except for the SDCM of Russia provide GPS-only augmentation message. There are several reasons (i.e. a low data-rate) why most SBAS systems cannot support the multi-constellation GNSS. In order to overcome the limitations of the existing L1-only SBAS MOPS and to improve the performance of the current operating SBAS systems, studies on the L1/L5 DFMC (Dual-Frequency, Multi-Constellation) SBAS are actively ongoing. FAA (Federal Aviation Administration) in United States and the ESA (European Space Agency) have held the SBAS IWG (Interoperability Working Group) and have continued to discuss the development of the L1/L5 DFMC SBAS. However, even if the development of the L1/L5 DFMC SBAS is completed, many users with a L1 single frequency and multi-constellation GNSS receiver, which occupies most of the GNSS receiver market share, cannot use the L1/L5 DFMC SBAS. Therefore, it is necessary to study on a method to improve the performance of the L1-only SBAS. We propose to remove the fast corrections and to assign additional time slots for providing the long-term corrections of GLONASS and other constellations. As we had already proven at the ION ITM 2017, the PRC (Pseudo-Range Correction) in MT (Message Type) 2 to 5 needs not to be broadcast every 6 seconds, and it can be included to the satellite clock correction term in MT 25 after being converted into the unit of second. If the fast correction is not broadcast, half of the time slots are available and enough to send the long-term corrections for other constellations than GPS. And, we generated the long-term corrections for GLONASS satellites using GLONASS satellite precise ephemeris from the IAC (Information and Analysis Center). GLONASS long-term corrections were packed in MT 25 and these additional messages were scheduled in the empty time slots obtained by removing the fast correction. In this paper, we suggested to remove the fast correction and to modify the broadcasting timing and very few parameters of the current L1 SBAS message. We also showed that even this minor modification is working with the live SBAS message and effective to reduce the size of the protection level by supporting the multi-constellation GNSS, which will also contribute to improve the performance of integrity, availability and continuity.

We study the dynamics of cyclic competing mobile five species on spatially extended systems originated from asymmetric initial populations and investigate the basins for the three possible asymptotic states, coexistence of all species, existences of only two independent species, and the extinction. Through extensive numerical simulations, we find a prosperous dependence on initial conditions for species biodiversity. In particular, for fixed given equal densities of two relevant species, we find that only five basins for the existence of two independent species exist and they are spirally entangled for high mobility. A basin of coexistence is outbreaking when the mobility parameter is decreased through a critical value and surrounded by the other five basins. For fixed given equal densities of two independent species, however, we find that basin structures are not spirally entangled. Further, final states of two independent species are totally different. For all possible considerations, the extinction state is not witnessed which is verified by the survival probability. To provide the validity of basin structures from lattice simulations, we analyze the system in mean-field manners. Consequently, results on macroscopic levels are matched to direct lattice simulations for high mobility regimes. These findings provide a good insight into the fundamental issue of the biodiversity among many species than previous cases.

A new LQG based vector tracking algorithm using additional tracking loops for high disturbance environment is presented. The conventional vector tracking algorithm does not estimate errors such as atmospheric delay error and multipath because vector tracking algorithm first estimates the position and estimates the measurements. Therefore, additional tracking loops defined as range domain loop in this paper compensate for these errors to enable continuous signal tracking. In order to evaluate the performance of the proposed algorithm, we compare the LQG based vector tracking algorithm with the EKF and loop filter based vector tracking algorithm and confirm that the LQG based vector tracking algorithm is more robust than EKF based vector tracking algorithm especially in a dynamic user environment. In addition, we confirm that the LQG based vector tracking algorithm with range domain loop can maintain the signal tracking successively in high disturbance environment caused by multiple error sources. Finally, LQG based vector tracking algorithm with range domain loop can be similar results compared to LQG-VTL in no disturbance environment.

Time synchronization system using dual frequency bands is designed and the error sources are analyzed for alternative synchronized-pseudolite navigation system (S-PNS) which aims at military application. To resolve near/far problem, dual frequency band operation is proposed instead of pulsing transmission which degrades level of reception. In dual frequency operation H/W delay should be considered to eliminate errors caused by inter-frequency bias (IFB) difference between the receivers of the pseudolites and users. When time synchronization is performed across the sea, multipath error is occurred severely since the elevation angle between pseudolites is low so total reflection can be happened. To investigate the difference of multipath effects according to location, pseudolites are set up coastal area and land area and performances are compared. The error source related with tropospheric delay is becoming dominant source as the coverage of the PNS is broadening. The tropospheric delay is measured by master pseudolite receiver directly using own pseudorange and slave pseudorange. Flight test is performed near coastal area using S-PNS equipped with developed time synchronization system and test results are also presented.

Alternative strategy is common in animal populations to promote reproductive fitness by obtaining resources. In spatial dynamics of cyclic competition, reproduction can occur when individuals obtain vacant rooms and, in this regard, empty sites should be resources for reproduction which can be induced by interspecific competition. In this paper, we study the role of alternative competition in the spatial system of cyclically competing five species by utilizing rock-paper-scissors-lizard-spock game. From Monte-Carlo simulations, we found that strong alternative competition can lead to the reemergence of coexistence of five species regardless of mobility, which is never reported in previous works under the symmetric competition structure. By investigating the coexistence probability, we also found that coexistence alternates by passing certain degrees of alternative competition in combination with mobility. In addition, we provided evidences in the opposite scenario by strengthening spontaneous competition, which exhibits the reemergence of coexistence similarly. Our findings may suggest more comprehensive perspectives to interpret mechanisms for biodiversity by alternative strategies in spatially extended systems than previously reported.

The role of mutation, which is an error process in gene evolution, in systems of cyclically competing species has been studied from various perspectives, and it is regarded as one of the key factors for promoting coexistence of all species. In addition to naturally occurring mutations, many experiments in genetic engineering have involved targeted mutation techniques such as recombination between DNA and somatic cell sequences and have studied genetic modifications through loss or augmentation of cell functions. In this paper, we investigate nonlinear dynamics with targeted mutation in cyclically competing species. In different ways to classic approaches of mutation in cyclic games, we assume that mutation may occur in targeted individuals who have been removed from intraspecific competition. By investigating each scenario depending on the number of objects for targeted mutation analytically and numerically, we found that targeted mutation can lead to persistent coexistence of all species. In addition, under the specific condition of targeted mutation, we found that targeted mutation can lead to emergences of bistable states for species survival. Through the linear stability analysis of rate equations, we found that those phenomena are accompanied by Hopf bifurcation which is supercritical. Our findings may provide more global perspectives on understanding underlying mechanisms to control biodiversity in ecological/biological sciences, and evidences with mathematical foundations to resolve social dilemmas such as a turnover of group members by resigning with intragroup conflicts in social sciences.

In the past decade, there have been many efforts to understand the species interplay with biodiversity in cyclic games within the macro and microscopic levels. In this direction, mobility and intraspecific competition have been found to be the main factors promoting coexistence in spatially extended systems. In this paper, we explore the relevant effect of asymmetric competitions coupled with mobility on the coexistence of cyclically competing species. By examining the coexistence probability, we have found that mobility can facilitate coexistence in the limited cases of asymmetric competition and can be well predicted by the basin structure of the deterministic system. In addition, it is found that mobility can have beneficial and harmful effects on coexistence when all competitions occur asymmetrically. We also found that the coexistence in the spatial dynamics ultimately becomes a global attractor. We hope to provide insights into the associated effects of asymmetric interplays on species coexistence in a spatially extended system and understand the biodiversity of asymmetrically competitive species under more complex competition structures.

Conflict that arises between two groups of different paradigms is an inevitable phenomenon, and a representative example of the conflict among different groups is a conflict phenomenon caused by competition among political parties. In this paper, we study the dynamical behavior of a political party system. Considering three major political parties, we investigate how political party systems can be changed by employing a mathematical model. By considering the transfer mechanism of recruitment as well as conflict of competition between political parties, we found that all parties are likely to coexist when both the competition and transfer between the parties are weak, or if either mechanism can occur at a relatively low level. Otherwise, a political party system is changed to a single-party system. In addition, we found that when a party system was changed into a single-party system, it appeared to be either bistable or multistable, and has been elucidate by linear stability analysis. Our results may provide insights to understand mechanisms how political party systems can be changed by conflict and transfer.

This article reports a numerical study of natural convection in a vertical annulus filled with a fluid-saturated porous medium, and with internal heat generation subject to a discrete heating from the inner wall. The relative importance of discrete heating on natural convection in the porous annulus is examined via the Brinkman-extended Darcy equation. The inner wall of the annulus has a discrete heat source and the outer wall is isothermally cooled at a lower temperature. The top and bottom walls and the unheated portions of the inner wall are kept adiabatic. The governing equations are numerically solved using an implicit finite difference method. A wide range of numerical simulations is conducted to understand the effects of various parameters like heat source length, heat source location, Darcy number, radius ratio, and Rayleigh numbers due to external and internal heating on the flow and heat transfer. The numerical results reveal that the placement of the heater near the middle portion of the inner ...

When pseudolite navigation system is applied to wide area, the tropospheric delay is the main error factor. In this study, we experimentally compared and analyzed the performance of the conventional pseudolite tropospheric delay models. The integration method using radiosonde meteorological data was suggested to derive the reference value for the comparison and analysis. Flight tests were carried out to analyze the performance of the tropospheric delay models according to the elevation angle and distance conditions between the user receiver and the pseudolite. As the results of this study, we provided the basis for the choice of tropospheric delay model appropriate to the relative location characteristics of the pseudolite and the user.