Direct Measurement of Fast Transients by Using Boot-strapped Waveform Averaging

An approximation to coherent sampling, also known as boot-strapped waveform averaging, is presented. The method uses digital cavities to determine the condition for coherent sampling. It can be used to increase the effective sampling rate of a repetitive signal and the signal to noise ratio simultaneously. The method is demonstrated by using it to directly measure the fluorescence lifetime from rhodamine 6G by digitizing the signal from a fast avalanche photodiode. The obtained lifetime of 4.4+-0.1 ns is in agreement with the known values

Generalized lock-in amplifier for precision measurement of high frequency signals

We herein formulate the concept of a generalized lock-in amplifier for the precision measurement of high frequency signals based on digital cavities. Accurate measurement of signals higher than 200 MHz using the generalized lock-in is demonstrated. The technique is compared with a traditional lock-in and its advantages and limitations are discussed. We also briefly point out how the generalized lock-in can be used for precision measurement of giga-hertz signals by using parallel processing of the digitized signals

High Precision Measurements Using High Frequency Signals

Generalized lock-in amplifiers use digital cavities with Q-factors as high as 5X10^8. In this letter, we show that generalized lock-in amplifiers can be used to analyze microwave (giga-hertz) signals with a precision of few tens of hertz. We propose that the physical changes in the medium of propagation can be measured precisely by the ultra-high precision measurement of the signal. We provide evidence to our proposition by verifying the Newton's law of cooling by measuring the effect of change in temperature on the phase and amplitude of the signals propagating through two calibrated cables. The technique could be used to precisely measure different physical properties of the propagation medium, for example length, resistance, etc. Real time implementation of the technique can open up new methodologies of in-situ virtual metrology in material design

To what extent does surrounding landscape explain stand-level occurrence of conservation-relevant species in fragmented boreal and hemi-boreal forest?-a systematic review protocol

Background: Silviculture and land-use change has reduced the amount of natural forest worldwide and left what remains confined to isolated fragments or stands. To understand processes governing species occurrence in such stands, much attention has been given to stand-level factors such as size, structure, and deadwood amount. However, the surrounding matrix will directly impact species dispersal and persistence, and the link between the surrounding landscape configuration, composition and history, and stand-level species occurrence has received insufficient attention. Thus, to facilitate optimisation of forest management and species conservation, we propose a review addressing 'To what extent does surrounding landscape explain stand-level occurrence of conservation-relevant species in fragmented boreal and hemi-boreal forest?'.Methods: The proposed systematic review will identify and synthesise relevant articles following the CEE guidelines for evidence synthesis and the ROSES standards. A search for peer-reviewed and grey literature will be conducted using four databases, two online search engines, and 36 specialist websites. Identified articles will be screened for eligibility in a two-step process; first on title and abstract, and second on the full text. Screening will be based on predefined eligibility criteria related to a PECO-model; population being boreal and hemi-boreal forest, exposure being fragmentation, comparator being landscapes with alternative composition, configuration, or history, and outcome being occurrence (i.e., presence and/or abundance) of conservation-relevant species. All articles that pass the full-text screening will go through study validity assessment and data extraction, and be part of a narrative review. If enough studies prove comparable, quantitative meta-analyses will also be performed. The objective of the narrative review and the meta-analyses will be to address the primary question as well as six secondary questions, and to identify important knowledge gaps

Mosquito Feeding Affects Larval Behaviour and Development in a Moth

Organisms are attacked by different natural enemies present in their habitat. While enemies such as parasitoids and predators will kill their hosts/preys when they successfully attack them, enemies such as micropredators will not entirely consume their prey. However, they can still have important consequences on the performance and ecology of the prey, such as reduced growth, increased emigration, disease transmission

Digital Hardware Aspects of Multiantenna Algorithms

The field of wireless communication is growing rapidly, with new requirements for the next generation of mobile and wireless communications technology. In order to achieve the capacities needed for future wireless systems, the design and implementation of advanced communications techniques such as multiantenna systems is required. These systems are realized by computationally complex algorithms, requiring new digital hardware architectures to be developed. The development of efficient and scalable hardware building blocks for realization of multiantenna algorithms is the focus of this thesis. The first part of the thesis deals with the implementation of complex valued division. Two architectures implementing a numerically robust algorithm for computing complex valued division with standard arithmetic units are presented. The first architecture is based on a parallel computation scheme offering high throughput rate and low latency, while the second architecture is based on a resource conservative time-multiplexed computation scheme offering good throughput rate. The two implementations are compared to an implementation of a CORDIC based complex valued division. The second part of the thesis discusses implementation aspects of fundamental matrix operations found in many multiantenna algorithms. Four matrix operations were implemented; triangular matrix inversion, QR-decomposition, matrix inversion, and singular value decomposition. Matrix operations are usually implemented using large arrays of processors, which are difficult to scale and consume a lot of resources. In this thesis a method based on the data flow was applied to map the algorithms to scalable linear arrays. An even more resource conservative design based on a single processing element was also derived. All the architectures are capable of handling complex valued data necessary for the implementation of communication algorithms. In the third part of the thesis, developed building blocks are used to implement the Capon beamformer algorithm. Two architectures are presented; the first architecture is based on a linear data flow, while the second architecture utilizes the single processing element architecture. The Capon beamformer implementation is going to be used in a channel sounder to determine the direction-of-arrival of impinging signals. Therefore it was important to derive and implement flexible and scalable architectures to be able to adapt to different measuring scenarios. The linear flow architecture was implemented and tested with measured data from the channel sounder. By analyzing each block in the design, a minimum wordlength design could be derived. The fourth part of the thesis presents a design methodology for hardware implementation on FPGA

Read and store data in JSON format for smart sensor : A comparison in response time between the hybrid database PostgreSQL and MongoDB

Sociala media genererar stora mängder data men det finns fler saker som gör det och lagrar i NoSQL databassystem och smarta sensorer som registrerar elektrisk förbrukning är en av de. MongoDB är ett NoSQL databassystem som lagrar sin data i dataformatet JSONB. PostgreSQL som är ett SQL databassystem har i sina senare distributioner också börjat hantera JSONB. Det gör att PostgreSQL är en typ av hybrid då den hanterar operationer för både SQL och NoSQL. I denna studie gjordes ett experiment för att se hur dessa databassystem hanterar data för att läsa och skriva när det gäller JSON för smarta sensorer. Svarstider registrerades och försökte svara på hypotesen om PostgreSQL kan vara lämplig för att läsa och skriva JSON data som genereras av en smart sensor. Experimentet påvisade att PostgreSQL inte ökar svarstid markant när mängden data ökar för insert men för MongoDB gör det. Svaret på hypotesen om PostgreSQL kan vara lämplig för JSON data är att det är det möjligt att den kan vara det men svårt att svara på och ytterligare forskning behövs

Implementation of a Highly Scalable Architecture for Fast Inversion of Triangular Matrices

In this paper, an F'F'GA implementation of a novel and highly scalable hardware architecture for fast inversion of triangular matrices is presented. An integral part of modem signal processing and communications applications involves manipulation of large matrices. Therefore, scalable and flexible hardware architectures are increasingly sought for. In this paper, the traditional triangular shaped array architecture with n(n+1)/2 communicating processors, with n being the number of inputs, is mapped to a linear structure with only n processors, The linear and the triangular shaped architectures are compared in aspect of area consumption, latencies, and maximum clocking speed. This paper also show that the linear array structure avoids drawhacks such as non-scalability, large area, and large power consumption. The implementation is based on a numerically stahle recurrence algorithm, which has excellent properties for hardware implementation