Neural networks and MIMD-multiprocessors

Two artificial neural network models are compared. They are the Hopfield Neural Network Model and the Sparse Distributed Memory model. Distributed algorithms for both of them are designed and implemented. The run time characteristics of the algorithms are analyzed theoretically and tested in practice. The storage capacities of the networks are compared. Implementations are done using a distributed multiprocessor system

Effect of crop species and management practices on perennial weeds in organic farming

In order to study the biology and non-chemical control of perennial weeds, a three-year field experiment was established in 2001 at Vihti, southern Finland. The experiment was placed in a clay soil field under organic production, infested moderately with Cirsium arvense, Elymus repens and Stachys palustris, and heavily with Sonchus arvensis

Managing Sonchus arvensis using mechanical and cultural methods

Perennial sow-thistle (Sonchus arvensis L.) represents an increasing problem in Finland. Options for mechanical and cultural control of S. arvensis were studied in a field experiment on clay soil under organic production. The experiment consisted of different crop sequences: spring cereal (barley, Hordeum vulgare L., in 2001, oats, Avena sativa L., in 2002) with or without inter-row hoeing and/or stubble cultivation, bare fallow, fibre hemp (Cannabis sativa L.), and ley with mowing. In 2003 the entire field was sown to spring wheat. Crop plant and Sonchus shoot density and dry mass prior to cereal harvest and crop yield were assessed. The control effect was rated: bare fallow > ley > cereal with or without inter-row hoeing > poor growth fibre hemp. Bare fallow was an effective but costly way to reduce S. arvensis infestation. Introduction of a regularly mown green fallow or silage ley in the crop rotation is advisable. Mechanical weed control by inter-row hoeing in cereals limits S. arvensis growth. Infestation might also be reduced by stubble cultivation in autumn. When managing S. arvensis using mechanical and cultural methods, appropriate options, including a competitive crop, should be chosen for the specific field and rotation

Laboratory assessment of crop tolerance to selective flaming

We developed a laboratory method which enables researchers of thermal weed control to assess crop tolerance to selective flaming. We have tested cabbage and red beet tolerance to flaming with this method

Additive Manufactured Compliant Surface Reflectance Sensor

In this paper1, we present an additive manufacturing (AM) method to implement structural electronics using an off-the-shelf fused deposition modeling (FDM) 3D printer with thermoplastic polyurethane (TPU) filament, conductive silver ink, and electronics components in standard packages. As a demonstrator, a surface reflectance sensor has been implemented. The structure consists of several 3D-printed TPU layers, 3D channels for the conductors, and cavities for components. A comparison is made between the performance of a traditional implementation on rigid PCB and the new sensor. The study shows that the chosen approach can be used for AM structural electronics.Peer reviewe

Stretchable electronic devices for wearable and on-skin applications : Effects of material anisotropy and extensibility in simple stretchable systems

Stretchable electronics pose a great challenge for electrical designers since mechanical interaction between the parts of these platforms should be properly taken into account and cannot be neglected. This work represents an effort to highlight some mechanical effects related to the use of anisotropic components in this type of electronics; by developing separate finite element models for both textile and on-skin electronics, the authors aim to discuss mainly the effects of material orientation and limiting extensibility in the substrates used, which can heavily affect the electromechanical performance of printed stretchable electronic devices.acceptedVersionPeer reviewe

Electromechanical Properties of 3D-Printed Stretchable Carbon Fiber Composites

The addition of fillers has been implemented in fused filament fabrication (FFF), and robust carbon fillers have been found to improve the mechanical, electrical, and thermal properties of 3D-printed matrices. However, in stretchable matrices, the use of fillers imposes significant challenges related to quality and durability. In this work, we show that long carbon staple fibers in the form of permeable carbon fiber cloth (CFC) can be placed into a stretchable thermoplastic polyurethane (TPU) matrix to improve the system. Four CFC sample series (nominally 53–159-µm-thick CFC layers) were prepared with a permeable and compliant thin CFC layer and a highly conductive and stiff thick CFC layer. The sample series was tested with single pull-up tests and cyclic tensile tests with 10,000 cycles and was further studied with digital image correlation (DIC) analyses. The results showed that embedded CFC layers in a TPU matrix can be used for stretchable 3D-printed electronics structures. Samples with a thin 53 µm CFC layer retained electrical properties at 50% cyclic tensile deformations, whereas the samples with a thick >150-µm CFC layer exhibited the lowest resistance (5 Ω/10 mm). Between those structures, the 106-µm-thick CFC layer exhibited balanced electromechanical properties, with resistance changes of 0.5% in the cyclic tests after the orientation of the samples. Furthermore, the suitability of the structure as a sensor was estimated.publishedVersionPeer reviewe

Hybrid Material Extrusion Process Optimization for Printability and Adhesion in 3D-Printed Electronics

3D printing exhibits strong potential in electronics manufacturing for its capability of manufacturing complex structures with a wide range of materials. However, thermoplastic polyurethane (TPU) has rarely been fabricated by 3D printing for electronics due to the limited understanding of its printability and the adhesion of the conductors on it. Herein, we invetigate the printability of TPU using varying layer height and printing temperature in the Materials Extrusion (MEX) process, their impacts on the printability, and the adhesion of conductive trace on TPU. The printability is characterized by the surface roughness, stability of dimension and mass, and the adhesion is evaluated by a standard cross-cutting method. In this research, 0.20 mm layer height and 220 °C printing temperature have consistently proven to be optimal configuration parameters for MEX printing of TPU. Larger layer height in TPU printing causes poorer printing quality (lower dimensional accuracy, more porous structure, rougher surface), lower ink–TPU adhesion, and transforms the adhesive failure of ink against peeling to cohesive failure. Higher printing temperature causes less homogeneous structure and rougher surface with minor influence on the width and conductivity of ink on TPU, and no influence on the mechanism of ink failure against peeling.Peer reviewe

Dormancy of vegetative reproduction in some perennial weeds

In a joint experiment between Norway, Denmark, Finland and Sweden the dormancy of vegetative reproduction in Cirsium arvense, Sonchus arvensis and Elymus repens was studied during the latter part of the vegetation period.The aim of the study was to achieve a more efficient control of these weed species by knowing their reproduction behaviour in the autumn