Cross-layer framework and optimization for efficient use of the energy budget of IoT Nodes

Both physical and MAC-layer need to be jointly optimized to maximize the autonomy of IoT devices. Therefore, a cross-layer design is imperative to effectively realize Low Power Wide Area networks (LPWANs). In the present paper, a cross-layer assessment framework including power modeling is proposed. Through this simulation framework, the energy consumption of IoT devices, currently deployed in LoRaWAN networks, is evaluated. We demonstrate that a cross-layer approach significantly improves energy efficiency and overall throughput. Two major contributions are made. First, an open-source LPWAN assessment framework has been conceived. It allows testing and evaluating hypotheses and schemes. Secondly, as a representative case, the LoRaWAN protocol is assessed. The findings indicate how a cross-layer approach can optimize LPWANs in terms of energy efficiency and throughput. For instance, it is shown that the use of larger payloads can reduce up to three times the energy consumption on quasi-static channels yet may bring an energy penalty under adverse dynamic conditions

Efficient DSP and Circuit Architectures for Massive MIMO: State-of-the-Art and Future Directions

Massive MIMO is a compelling wireless access concept that relies on the use of an excess number of base-station antennas, relative to the number of active terminals. This technology is a main component of 5G New Radio (NR) and addresses all important requirements of future wireless standards: a great capacity increase, the support of many simultaneous users, and improvement in energy efficiency. Massive MIMO requires the simultaneous processing of signals from many antenna chains, and computational operations on large matrices. The complexity of the digital processing has been viewed as a fundamental obstacle to the feasibility of Massive MIMO in the past. Recent advances on system-algorithm-hardware co-design have led to extremely energy-efficient implementations. These exploit opportunities in deeply-scaled silicon technologies and perform partly distributed processing to cope with the bottlenecks encountered in the interconnection of many signals. For example, prototype ASIC implementations have demonstrated zero-forcing precoding in real time at a 55 mW power consumption (20 MHz bandwidth, 128 antennas, multiplexing of 8 terminals). Coarse and even error-prone digital processing in the antenna paths permits a reduction of consumption with a factor of 2 to 5. This article summarizes the fundamental technical contributions to efficient digital signal processing for Massive MIMO. The opportunities and constraints on operating on low-complexity RF and analog hardware chains are clarified. It illustrates how terminals can benefit from improved energy efficiency. The status of technology and real-life prototypes discussed. Open challenges and directions for future research are suggested.Comment: submitted to IEEE transactions on signal processin

Integrated risk assessment of selected mycotoxins in fresh produce and derived food products throughout the food chain, affected by climate changes and globalization

Fruits and vegetables are an important part of a healthy diet, and their consumption is expected to increase in the future because of health promotion. However, climate change and globalization will have an effect on their food safety (Paterson & Lima 2010). In order to maintain the desired level of food safety in Europe, it is necessary to explore new food contamination pathways and approaches to deal with these projected changes. An imported food safety problem is the presence of fungi and mycotoxins. (Semi) dried plants are mainly associated with mycotoxins but recently fresh produce are associated with new emerging mycotoxins. The objective of the research is to develop a farm-to-fork risk assessment model to predict the mycotoxin concentration in fresh and derived products in order to predict future risks due to climate change and growing import of foods from third countries. An initial inventory is made of relevant moulds and mycotoxins present on fresh produce and derived food products. Therefore data of mycotoxin concentration on dried plant, fresh and derived products are collected. This is done in cooperation with ICPC partners (e.g. Egypt, Brazil, Serbia and India) and is extended with European and national data. The data are obtained by including both scientific articles and grey literature (e.g. EFSA, RASFF). Most data are found from dried products, such as nuts, dried fruits and spices and herbs. Almost no data is available on fresh produce. To collect additional information (on fresh produce and derived products) a screening method with LC-TOF-MS is running for ochratoxin A, fumonisin B1, B2, B3, alternariol and alternariol monomethyl ether in tomatoes, onions, sweet bell peppers and soft red fruits. The MS parameters were tuned for each mycotoxin and both positive and negative electrospray conditions were checked. It was decided to screen for the mycotoxins in two separated runs (positive and negative electrospray run). The six mycotoxins can be screened in one sample in a relative short time of one hour. To screen for patulin we performed an non quantitative method with an HPLC with an extraction method described by Sanzani et al. (Sanzani et al. 2009). Preliminary results showed a presence of 14% of patulin in mouldy tomatoes (15 out of 107)

Direct electrodeposition of aluminium nano-rods

Electrodeposition of aluminium within an alumina nano-structured template, for use as high surface area current collectors in Li-ion microbatteries, was investigated. The aluminium electrodeposition was carried out in the ionic liquid 1-ethyl-3-methylimidazolium chloride:aluminium chloride (1:2 ratio). First the aluminium electrodeposition process was confirmed by combined cyclic voltammetry and electrochemical quartz crystal microbalance measurements. Then, aluminium was electrodeposited under pulsed-potential conditions within ordered alumina membranes. A careful removal of the alumina template unveiled free standing arrays of aluminium nano-rods. The nano-columns shape and dimensions are directly related to the template dimensions. To our knowledge, this is the first time that direct electrodeposition of aluminium nano-pillars onto an aluminium substrate is reported

High precision hybrid RF and ultrasonic chirp-based ranging for low-power IoT nodes

Hybrid acoustic-RF systems offer excellent ranging accuracy, yet they typically come at a power consumption that is too high to meet the energy constraints of mobile IoT nodes. We combine pulse compression and synchronized wake-ups to achieve a ranging solution that limits the active time of the nodes to 1 ms. Hence, an ultra low-power consumption of 9.015 µW for a single measurement is achieved. The operation time is estimated on 8.5 years on a CR2032 coin cell battery at a 1 Hz update rate, which is over 250 times larger than state-of-the-art RF-based positioning systems. Measurements based on a proof-of-concept hardware platform show median distance error values below 10 cm. Both simulations and measurements demonstrate that the accuracy is reduced at low signal-to-noise ratios and when reflections occur. We introduce three methods that enhance the distance measurements at a low extra processing power cost. Hence, we validate in realistic environments that the centimeter accuracy can be obtained within the energy budget of mobile devices and IoT nodes. The proposed hybrid signal ranging system can be extended to perform accurate, low-power indoor positioning

A Case Report of Hodgkin's Lymphoma in a Patient with Carcinosarcoma of the Bladder

The screening of patients with a known primary extrathoracic malignancy for pulmonary metastasis may result in the identification of solitary or multiple pulmonary nodules. Radiologic features of these pulmonary nodules may suggest a diagnosis, but these features cannot reliably distinguish between benign and malignant etiologies. We present the case of a patient, diagnosed with carcinosarcoma of the bladder, who was found to have multiple pulmonary nodules by CT evaluation. Physical examination of the patient demonstrated the presence of cervical and axillary lymphadenopathy. An excisional biopsy of an axillary lymph node confirmed the diagnosis of Hodgkin's lymphoma. This case report demonstrates that radiographic information obtained by CT scan must be carefully correlated with the history and physical examination of the patient. This case report also demonstrates the importance of diagnostic biopsy of pulmonary nodularity discovered in patients with a known primary extrathoracic malignancy. The assumption that these pulmonary nodules represented metastatic malignancies would have had crucial prognostic and therapeutic implications

Farm to fork risk assessment of emerging mycotoxins in fresh produce : the case of tomato considering climate change

The overall objective of the presented work was to establish a farm to fork risk assessment of emerging mycotoxins in fresh produce and derived products in view of the pressure of potential climate change scenarios and increasing import across European borders. A first objective of this work was gaining insights in the potential presence and characterization of emerging mycotoxins in fresh produce and their derived products. Therefore, a multiple mycotoxin extraction and detection method was developed. Based on those results it was decided to work on the tomato case. Stability experiments during the processing of derived tomato products were performed. A second objective of the presented work was the evaluation of pre-harvest conditions on mould growth and mycotoxin production during tomato cultivation. Models were developed for the growth of Alternaria arborescens and the influence of climate change on mould growth was evaluated for two productions regions: Spain and Poland. The third objective of the presented study was a risk assessment calculation on the emerging mycotoxins and their discussion in view of established mycotoxins in plant products

The combined and interactive effects of zinc, temperature and phosphorus on freshwater planktonic communities

The main goal of the ecological risk assessment of chemicals (ERA) is the protection of populations and communities and the correct effect assessment of chemicals on the structure and functioning of aquatic ecosystems. At present, ERA is mainly based on data obtained from standard ecotoxicity experiments. These experiments are typically conducted under standardized optimal conditions, at the species level and exposed at a single stressor at the time. However, these general ERA approaches are in sharp contrast with natural conditions. Natural populations and communities are often exposed to a mixture of multiple stressors that are biotic (e.g. food shortage, predation) and abiotic (e.g. eutrophication, non-optimal temperature or water chemistry, metals). Species interactions such as predation and competition for food are two major biotic factors that are able to significantly affect the responses of organisms to toxicants. Additionally, abiotic factors such as temperature (T) can also play an important role affecting the toxic effects of chemical pollutants (e.g. by influencing its bioavailability and toxicokinetics). Therefore, by ignoring ecological interactions and by not considering natural field conditions these single-species tests oversimplify the actual field situation and ERA may not be protective. The aim of this PhD thesis was to investigate the combined effect of Zn with natural environmental stressors (temperature and/or phosphorous) at different organization levels (population vs. community) on freshwater organisms in order to increase the realism of current ERA