The need for monitoring of processes and equipment has been identified as a major driver for digitalization in process industries. With an ageing workforce and plant infrastructure, process plants need a means of ensuring the performance of their facilities in order to remain competitive. One approach is through more widespread and effective process and equipment monitoring to detect anomalies or identify opportunities for plant efficiency improvements. Monitoring tasks in process automation are classified as noncritical measurements that have no immediate impact on the business. Being non-critical, slow to develop and with a deferred impact, measurements for monitoring are often hard to justify. In many instances, such measurements are taken manually in a scheduled manner. Following this approach, operators have to live with the trade-off between manpower costs and the effectiveness and coverage of the checks. This approach, therefore, cannot be scaled up without dramatic cost increases. Indeed, the advent of a technology that is competitive with manpower costs would be the enabler for the more widespread use of monitoring technologies. In this paper, we present an approach to analyze cost-benefit structures that can be used to help guide the development of sensing solutions for monitoring applications. The approach is applied to the widespread and relevant example of pump aggregate monitoring. As a result, cost targets for sensor developments are identified. Relevance and some peculiarities of the use of low-cost sensing (LCS) elements are briefly discussed, as well as trends of recent product developments.
Electrical substations transform voltage from high to low, or low to high for distribution and transmission, respectively, and are a critical part of our electricity infrastructure. The state of a substation is continuously measured for monitoring, controlling and protection purposes, using synchrophasor measurements. The IEC 61850 standard defines communication protocols for electrical substations, including transmission of synchrophasor measurements. However, IEC 61850 does not properly address cyber security, leaving this critical infrastructure highly vulnerable to cyber attacks. This paper describes the development and testing of a novel mechanism for delayed integrity check for synchrophasor measurements. The results show that the solution manages to detect when integrity of the synchrophasor transmission is compromised, without adding any delay to the time-critical synchrophasor transmission itself.
Standardized by the 3rd Generation Partnership Project (3GPP) and introduced in release 13, the Narrowband-IoT (NB-IoT) technology seems well suited for wireless IoT end devices with low power consumption, low data throughput, and long-range communication requirements, which need to control and monitor environmental conditions in remote and harsh locations. However, being NB-IoT an emerging technology, it is necessary to study its reliability under such use-case scenarios. This paper presents an NB-IoT coverage analysis in the North region of Portugal under various environment scenarios: indoor, underground, and inside an underground concrete dome with an iron cover, using a custom-developed NB-IoT end device equipped with the Quectel BC66 as the communication modem and a custom application executing over the Azure ThreadX RTOS. Our investigation leans over the coverage quality based on some indicators collected, such as RSRP, RSRQ, RSSI, ECL, PCI, and transmission power. The obtained results indicate that this technology is capable of satisfying the requirements of the most demanding IoT applications, with percentages of successful transmissions above 96%, even at distances greater than 1400m between the device and the communication infrastructure (LTE) cell, or even in regions with very low/noise floor coverage.
Interface automata have been introduced as a way to advance from value and domain descriptions of type systems to temporal interface descriptions. The original introduction of interface automata used a notion of buffered communication with infinite buffer size. This communication model is suitable to abstract the behaviour of many computing aspects with asynchronous communication between components. In this paper we present Loosely Synchronous Interface Automata (LSIA) to describe interfaces of components with loosely synchronised communication. Loosely synchronised communication facilitates a blocking semantics of communication for both sender and receiver. With loosely synchronisation it is possible to describe systems where a precise order of events is necessary. For example, cyber-physical systems often include control tasks where the exact order of events is necessary for a safe operation. With LSIAs it is possible to check compatibility of interface models including safety-relevant properties like lifeness. In this paper we describe the composition of LSIAs and show examples.
This paper proposes improved reactive tabu search for optimal vehicle routing of vehicles considering allocation of secondary depots in case of natural disasters. In recent years, many large-scale disasters have occurred in Japan and large-scale disasters may occur in the near future, unfortunately. In case of large-scale disasters, emergency relief supply logistics is an important issue since it will affect lives of evacuees. The proposed method modifies a stored method of a tabu list, introduces aspiration criteria, and applies a searched list using a hash function for simultaneously solving the optimal number of secondary depots, the optimal placement and the distribution areas of secondary depots, and the optimal routes of vehicles in the distribution area of secondary depots. It is verified that the proposed method can generate higher quality optimal vehicle routing and reduce computation time than the conventional reactive tabu search based method with actual evacuation facility data of Chiba City, which are planned to be used in case of natural disasters. The results are confirmed by Wilcoxon test.
