Design, development and field assessment of a controlled seed metering unit to be used in grain drills for direct seeding of wheat

AbstractA new controlled seed metering unit was designed and mounted on a common grain drill for direct seeding of wheat (DSW). It comprised the following main parts: (a) a variable-rate controlled direct current motor (DCM) as seed metering shaft driver, (b) two digital encoders for sensing the rotational speed of supplemental ground wheel (SGW) and seed metering shaft and (c) a control box to handle and process the data of the unit. According to the considered closed-loop control system, the designed control box regularly checked the revolution per minute (RPM) of seed metering shaft, as operation feedback, using its digital encoder output. The seeding rate was determined based on the calculated error signal and output signal of the digital encoder of the SGW. A field with four different levels of wheat stubble coverage (10%, 30%, 40% and 50%) was selected for evaluation of the fabricated seed metering unit (FSMU). The dynamic tests were conducted to compare the performance of installed FSMU on the grain drill and equipped grain drill with common seed metering unit (CSMU) at three forward speeds of 4, 6 and 8 (Km/h) for DSW. Results of the FSMU assessment demonstrated that an increase in forward speed of grain drill (FSGD) and stubble coverage did not significantly affect the seeding rate in the grain drill for DSW. Using the FSMU reduced the coefficient of variation (CV) by approximately 50%. Consequently, applying the FSMU on the common grain drill led to a desirable seeding rate at different forward speeds of the grain drill and stubble existence

A Modal Series Representation of Genesio Chaotic System

In this paper an analytic approach is devised to represent, and study the behavior of, nonlinear dynamic chaotic Genesio system using general nonlinear modal representation. In this approach, the original nonlinear ordinary differential equations (ODEs) of model transforms to a sequence of linear time- invariant ODEs. By solving the proposed linear ODEs sequence, the exact solution of the original nonlinear problem is determined in terms of uniformly convergent series. Also an efficient algorithm with low computational complexity and high accuracy is presented to find the approximate solution. Simulation results indicate the effectiveness of the proposed method.Comment: International Journal of Instrumentation and Control Systems (IJICS) Vol.2, No.3, July 201

Distinct ensembles in the noradrenergic locus coeruleus are associated with diverse cortical states

The noradrenergic locus coeruleus (LC) is a controller of brain and behavioral states. Activating LC neurons en masse by electrical or optogenetic stimulation promotes a stereotypical "activated" cortical state of high-frequency oscillations. However, it has been recently reported that spontaneous activity of LC cell pairs has sparse yet structured time-averaged cross-correlations, which is unlike the highly synchronous neuronal activity evoked by stimulation. Therefore, LC population activity could consist of distinct multicell ensembles each with unique temporal evolution of activity. We used nonnegative matrix factorization (NMF) to analyze large populations of simultaneously recorded LC single units in the rat LC. NMF identified ensembles of spontaneously coactive LC neurons and their activation time courses. Since LC neurons selectively project to specific forebrain regions, we hypothesized that distinct ensembles activate during different cortical states. To test this hypothesis, we calculated band-limited power and spectrograms of local field potentials in cortical area 24a aligned to spontaneous activations of distinct LC ensembles. A diversity of state modulations occurred around activation of different LC ensembles, including a typical activated state with increased highfrequency power as well as other states including decreased high-frequency power. Thus-in contrast to the stereotypical activated brain state evoked by en masse LC stimulation-spontaneous activation of distinct LC ensembles is associated with a multitude of cortical states.Peer reviewe

An empirical investigation of performance overhead in cross-platform mobile development frameworks

The heterogeneity of the leading mobile platforms in terms of user interfaces, user experience, programming language, and ecosystem have made cross-platform development frameworks popular. These aid the creation of mobile applications – apps – that can be executed across the target platforms (typically Android and iOS) with minimal to no platform-specific code. Due to the cost- and time-saving possibilities introduced through adopting such a framework, researchers and practitioners alike have taken an interest in the underlying technologies. Examining the body of knowledge, we, nonetheless, frequently encounter discussions on the drawbacks of these frameworks, especially with regard to the performance of the apps they generate. Motivated by the ongoing discourse and a lack of empirical evidence, we scrutinised the essential piece of the cross-platform frameworks: the bridge enabling cross-platform code to communicate with the underlying operating system and device hardware APIs. The study we present in the article benchmarks and measures the performance of this bridge to reveal its associated overhead in Android apps. The development of the artifacts for this experiment was conducted using five cross-platform development frameworks to generate Android apps, in addition to a baseline native Android app implementation. Our results indicate that – for Android apps – the use of cross-platform frameworks for the development of mobile apps may lead to decreased performance compared to the native development approach. Nevertheless, certain cross-platform frameworks can perform equally well or even better than native on certain metrics which highlights the importance of well-defined technical requirements and specifications for deliberate selection of a cross-platform framework or overall development approach

Catalytic cleavage of HEAT and subsequent covalent binding of the tetralone moiety by the SARS-CoV-2 main protease

Here we present the crystal structure of SARS-CoV-2 main protease (Mpro) covalently bound to 2-methyl-1-tetralone. This complex was obtained by co-crystallization of Mpro with HEAT (2-(((4-hydroxyphenethyl)amino)methyl)-3,4-dihydronaphthalen-1(2H)-one) in the framework of a large X-ray crystallographic screening project of Mpro against a drug repurposing library, consisting of 5632 approved drugs or compounds in clinical phase trials. Further investigations showed that HEAT is cleaved by Mpro in an E1cB-like reaction mechanism into 2-methylene-1-tetralone and tyramine. The catalytic Cys145 subsequently binds covalently in a Michael addition to the methylene carbon atom of 2-methylene-1-tetralone. According to this postulated model HEAT is acting in a pro-drug-like fashion. It is metabolized by Mpro, followed by covalent binding of one metabolite to the active site. The structure of the covalent adduct elucidated in this study opens up a new path for developing non-peptidic inhibitors

Fractional-Order Control of a Nonlinear Time-Delay System: Case Study in Oxygen Regulation in the Heart-Lung Machine

A fractional-order controller will be proposed to regulate the inlet oxygen into the heart-lung machine. An analytical approach will be explained to satisfy some requirements together with practical implementation of some restrictions for the first time. Primarily a nonlinear single-input single-output (SISO) time-delay model which was obtained previously in the literature is introduced for the oxygen generation process in the heart-lung machine system and we will complete it by adding some new states to control it. Thereafter, the system is linearized using the state feedback linearization approach to find a third-order time-delay dynamics. Consequently classical PID and fractional order controllers are gained to assess the quality of the proposed technique. A set of optimal parameters of those controllers are achieved through the genetic algorithm optimization procedure through minimizing a cost function. Our design method focuses on minimizing some famous performance criterions such as IAE, ISE, and ITSE. In the genetic algorithm, the controller parameters are chosen as a random population. The best relevant values are achieved by reducing the cost function. A time-domain simulation signifies the performance of controller with respect to a traditional optimized PID controller

Distinct ensembles in the noradrenergic locus coeruleus are associated with diverse cortical states

SignificanceBrainstem locus coeruleus (LC) noradrenergic neurons produce an arousal-related state characterized by a broadband increase in high-frequency oscillations. This perspective was built upon electrical or optogenetic stimulation that artificially activates LC neurons synchronously. This has led to the conceptual model that LC activation is associated with a single cortical state. Here, we show that natural, spontaneously occurring LC single-unit activity consists of ensembles with largely nonoverlapping activation dynamics. Spontaneous activations of different LC ensembles are associated with different cortical states. Our results suggest that the role of the LC in controlling a single type of cortical state associated with arousal is an oversimplification. Instead, ensembles of LC neurons may control a diverse multitude of cortical states

Noradrenergic locus coeruleus ensembles fire at distinct times to evoke different cortical states in rat prefrontal cortex

The Locus Coeruleus (LC), a noradrenergic brain stem nucleus projecting throughout the forebrain, is thought to act as an undifferentiated state controller across all forebrain targets because LC neurons spike synchronously [1, 2]. However, recent work demonstrated ensembles in the LC and therefore made targeted neuromodulation a possibility [3]. This recent study used graph theory to reveal a static snapshot of LC ensembles. In order to now demonstrate that LC ensembles cause targeted neuromodulation, it is necessary to resolve LC ensemble dynamics over time in relation to ongoing cortical states

Different Cortical States Emerge around Spontaneous Activations of Distinct Locus Coeruleus Ensembles

Various states of wakefulness, perceptual ability, and locomotor activity are associated with different cortical states defined by local field potential (LFP) oscillatory content. The brainstem nucleus, Locus Coeruleus (LC), contributes to cortical state via noradrenergic projections to nearly the entire central nervous system. Electrical or optogenetic LC stimulation evokes increased high-frequency (HF, >20 Hz) cortical LFP oscillations and decreased low-frequency (LF, <12 Hz) oscillations in anesthetized and non-anesthetized experiments and evokes awakening in sleeping mice. The LC stimulation-evoked cortical state is due to highly synchronous whole-LC neuronal activation because about 1600 neurons are densely packed into only about 200 × 500 × 1000μm (in rats) and stimulation even at the lower end of the current range used in these studies (30–50μA) evokes spikes 400um from the stimulation site. These studies established the conceptual model that LC generates a single aroused cortical state. Recently, however, recordings of spontaneous LC single unit spiking demonstrated that pairs of LC neurons have sparse, yet structured time-averaged cross-correlations that are uncharacteristic of the en masse population event elicited by LC stimulation. It remains unknown whether spontaneous LC population activity consists of multi-cell ensembles or how LC ensemble activity evolves over time. Here, we used non-negative matrix factorization (NMF) to analyze large populations of simultaneously recorded LC single units in the urethane anesthetized rat. NMF, unlike traditional time-averaged pairwise correlations, detects the precise neuronal composition of LC ensembles and the evolution of their activity over time. We found that LC population dynamics consists of ensembles of co-active neurons with largely non-overlapping activation dynamics. We then characterized the relationship between LC ensemble activation dynamics and cortical state. We calculated cortical LFP (area 24a) band-limited power and spectrograms aligned to spontaneous activations of LC ensembles. Spontaneous activation of distinct LC ensembles was associated with a diverse pool of cortical states. Depending on which LC ensemble fired, we observed a diverse state space of increased HF and LF, decreased HF and LF, and opposing HF and LF power. Thus, LC is not simply a switch controlling a single arousal-associated cortical state