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Cell-free massive MIMO systems consist of many distributed access points with simple components that jointly serve the users. In millimeter wave bands, only a limited set of predetermined beams can be supported. In a network that consolidates these technologies, downlink analog beam selection stands as a challenging task for the network sum-rate maximization. Low-cost digital filters can improve t

Climate change substantially affects plant phenology, resulting in earlier vegetation onset across temperate and boreal regions. Phenological shifts caused by warming may alter species interactions across trophic levels because of species-specific responses, and influence the reproductive success of dioecious species if the phenological sensitivity to warming (ST) differs between genders. We used

A hybrid combining T-matrix method and electric field integral equation is used to formulate fundamental bounds on radiation efficiency of an implanted antenna. Resulting quadratic optimization problem is solved using a dual formulation. The results present the versatility of the described computational scheme and show the optimal current densities that are the least impaired by dissipation in the

An algebraic link between transition matrix and impedance matrix is utilized in this work to unify characteristic mode decomposition originally proposed by Garbacz with a framework proposed later on by Harrington and Mautz. The resulting formulation is unique to all method of moments formulations, valid for all linear and lossless materials, and has many favorable properties. The unified prescript

Vehicle-to-everything (V2X) wireless communication is expected to play a key role in enabling complex Advanced Driving Assistance Applications, including the support of emerging autonomous vehicles. The development of V2X applications, especially safety-related, requires rigorous verification. Field trials, though, have to be supplemented with less expensive and more repeatable methods. Thorough V

This paper proposes a BP-based algorithm for sequential detection and estimation of MPC parameters based on radio signals. Under dynamic channel conditions with moving transmitter and/or receiver, the number of MPCs reflected from visible geometric features, the MPC dispersion parameters (delay, angle, Doppler frequency, etc), and the number of false alarm contributions are unknown and time-varyin

This paper presents an analysis of channel characteristics for an outdoor scenario at the frequency band of 28-30 GHz. A geometry-based clustering algorithm is proposed to group the measured multipath components (MPCs) based on the interaction points on the surrounding walls or objects obtained from Ray Tracing 3-D simulations, which is more physically interpretable than the traditional clustering

Algal blooms constitute an emerging threat to global inland water quality, yet their spatial and temporal distribution at the global scale remains largely unknown. Here we establish a global bloom database, using 2.91 million Landsat satellite images from 1982 to 2019 to characterize algal blooms in 248,243 freshwater lakes, representing 57.1% of the global lake area. We show that 21,878 lakes (8.

Cloud computing has emerged as a key technology in the latest decade and continues to be applied to manage the computing needs of new domains. As a result, the requirements on predictable behavior in the cloud increase, thus the hosted applications need to be recognized as both fault-tolerant and responsive even under difficult conditions.In this thesis, new modeling methods and decision-making st

Shelterbelts (or windbreaks) can effectively improve the microclimate and soil conditions of adjacent farmland and thus increase crop yield. However, the individual contribution of these two factors to yield changes is still unclear since the short-term effect from the microclimate and the accumulated effect from the soil jointly affect crop yield. The latter (soil effect) is supposed to remain af

The Earth is experiencing unprecedented climate change. Vegetation phenology has already showed strong response to the global warming, which alters mass and energy fluxes on terrestrial ecosystems. With technology and method developments in remote sensing, computer science and citizen science, many recent phenology-related studies have been focused on macrophenology. In this perspective, we 1) rev

The magnitude, direction and cause of precipitation changes across the Indo-Pacific Warm Pool (IPWP) during the Last Glacial Maximum (LGM) remain elusive. In particular, it is still inconclusive whether tropical or extra-tropical factors controlled such precipitation changes. Determining the spatio-temporal distribution of precipitation in the IPWP during the LGM is a valid strategy to address thi

While the Transformer architecture has become ubiquitous in the machine learning field, its adaptation to 3D shape recognition is non-trivial. Due to its quadratic computational complexity, the self-attention operator quickly becomes inefficient as the set of input points grows larger. Furthermore, we find that the attention mechanism struggles to find useful connections between individual points

Software development companies spend considerable time resolving bug reports. However, bug reports might be invalid, i.e., not point to a valid flaw. Expensive resources and time might be expended on invalid bug reports before discovering that they are invalid. In this case study, we explore the impact of invalid bug reports and develop and assess the use of machine learning (ML) to indicate wheth

Agricultural ecosystem water use efficiency (WUE) is an important indicator reflecting carbon-water coupling, but its control mechanisms in managed fields remain unclear. In order to reveal the influencing factors of WUE in the agricultural field under mulched drip irrigation (DM), we carried out the 8-year continuous observations in a maize field from Northwestern China. The structural equation m

Multi-source merging is an established tool for improving large-scale precipitation estimates. Existing merging frameworks typically use gauge-based precipitation error statistics and neglect the inter-dependence of various precipitation products. However, gauge-observation uncertainties at daily and sub-daily time scales can bias merging weights and yield sub-optimal precipitation estimates, part

The production, transport, and deposition of mineral dust exert major influences on climate change and Earth’s biogeochemical cycles. Furthermore, their imprint, as recorded in pelagic sediments, provides an avenue for determining past changes in terrestrial aridity and atmospheric circulation patterns in response to global climate change. Here, by examining geochemical and magnetic data obtained

For assembly tasks, the knowledge of both trajectory and forces are usually required. Consequently, we may use kinesthetics or teleoperation for recording human demonstrations. In order to have a more natural interaction, the operator has to be provided with a sense of touch. We propose a bilateral teleoperation system which is customized for this purpose. We introduce different coordinate frames

The aim of this work is to investigate different methods to solve the problem of allocating the correct amount of resources (network bandwidth and storage space) to video camera systems. Here we explore the intersection between two research areas: automatic control and game theory. Camera systems are a good example of the emergence of the Internet of Things (IoT) and its impact on our daily lives

Over the last decades, dramatic improvements in combinatorialoptimisation algorithms have significantly impacted artificialintelligence, operations research, and other areas. These advances,however, are achieved through highly sophisticated algorithms that aredifficult to verify and prone to implementation errors that can causeincorrect results. A promising approach to detect wrong results is tous