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There is a gap in literature on comparisons between different MPC optimal control formulations and solver choices for the same building HVAC system. Mixed Integer Nonlinear (MINL) formulations are rarely considered, despite being the most physically accurate way to represent HVAC systems. This work compares several MPC formulations, including Quadratic, Nonlinear, and MINL, applied to a case study building and investigates benefits and challenges of MINL MPCs from practical perspectives. Ten different MPC formulations were developed and implemented using Pyomo. Then, a detailed emulator model was developed using open-source Modelica libraries and used with BOPTEST to assess the performance of each MPC. Results show that convergence and control switching behaviours of MINL MPCs are sensitive to formulations, initialization approaches, solver selections, and solver parameters. Thus, they require significant effort for tuning. However, a very well-tuned MINL MPC performed similarly to successful Nonlinear MPC formulations.

Purpose To better respond to user needs for personalized information services in the context of academic libraries, this study aims at developing a prototype to provide mobile curation services by using the concept of content curation. Design/methodology/approach This study used a mobile application software development process, which consisted of five phases: user and organizational requirements, architecture design, navigation design, page design and implementation and usability testing. Usability testing was conducted with a total of 20 college students by online surveys at a university. Findings Meta-analysis identified key user needs: diversification of services, more personalized services, active communication with librarians, quality improvement of information and interface improvement. User and organizational requirements derived four main service modules – namely, Curation Services, Live Chat, My Page and My Log. Usability testing regarding ease of use, perceived usefulness and satisfaction indicated that participants were satisfied with the prototype. Research limitations/implications The study extends the discussion of quality academic library services by introducing the concept of content curation that uses the advantages of mobile technologies to overcome existing limitations in library services insufficient for meeting individual user needs. Originality/value Although many studies have discussed mobile library services, few studies have focused on developing a system for such services. The model developed in the study fills the research gap. Above all, the key modules specified by the prototype – Curation Services, Live Chat, My Page and My Log services – are expected to improve existing research and learning support services currently offered by academic libraries.

In this paper, a gray-box dynamic modeling approach for direct-expansion cooling systems is presented. The overall approach incorporates a multi-stage training procedure that consists of 1) identification of component sub-models from quasi-steady-state performance data, 2) system model integration with estimation of refrigerant charge and 3) fine tuning of thermal capacitances of the evaporator and condenser to capture the system dynamic responses. Compared to traditional physics-based models, the proposed modeling approach has advantages including reduced engineering efforts in the model development phase, improved computational efficiency and enhanced prediction accuracy. The modeling method was validated using a 3-ton variable-speed heat pump and proved to be capable of accurately predicting the system transient behaviors over a wide range of operating conditions. The established dynamic model was then applied for control stability analysis, with a specific goal of determining a proper control execution time step. The case study results showed that the stable control execution time step could change significantly, from 3 sec to 19 sec, as the operating conditions and control settings vary, and a proper selection of the execution time step is critical to ensure stable and reliable operations.

Frost accumulation is a common but undesired phenomenon for air-source heat pump (ASHP) systems in winter operations. Reverse-cycle defrosting that applies heat to the outdoor coil by reversing the thermodynamic cycle, is one of the predominant means for periodic removal of the accumulated frost. This paper presents a dynamic modeling framework for ASHPs under cycling of frosting and reverse-cycle defrosting operations. A uniform model structure was applied to frost formation and melting models, which were incorporated into the evaporator model, without a need for reinitializing the system when the operating mode switches between heating and defrosting. The developed model was simulated to predict transients of a residential ASHP under multiple cycles of frosting and defrosting operations, and results yielded good agreement with measurements.

Globalization and climate change have contributed to the simultaneous increase and spread of arboviral diseases. Cocirculation of several arboviruses in the same geographic region provides an impetus to study the impacts of multiple concurrent infections within an individual vector mosquito. Here, we describe coinfection and superinfection with the Mayaro virus (Togaviridae, Alphavirus) and Zika virus (Flaviviridae, Flavivirus) in vertebrate and mosquito cells, as well as Aedes aegypti adult mosquitoes, to understand the interaction dynamics of these pathogens and effects on viral infection, dissemination, and transmission. Aedes aegypti mosquitoes were able to be infected with and transmit both pathogens simultaneously. However, whereas Mayaro virus was largely unaffected by coinfection, it had a negative impact on infection and dissemination rates for Zika virus compared to single infection scenarios. Superinfection of Mayaro virus atop a previous Zika virus infection resulted in increased Mayaro virus infection rates. At the cellular level, we found that mosquito and vertebrate cells were also capable of being simultaneously infected with both pathogens. Similar to our findings in vivo, Mayaro virus negatively affected Zika virus replication in vertebrate cells, displaying complete blocking under certain conditions. Viral interference did not occur in mosquito cells. IMPORTANCE Epidemiological and clinical studies indicate that multiple arboviruses are cocirculating in human populations, leading to some individuals carrying more than one arbovirus at the same time. In turn, mosquitoes can become infected with multiple pathogens simultaneously (coinfection) or sequentially (superinfection). Coinfection and superinfection can have synergistic, neutral, or antagonistic effects on viral infection dynamics and ultimately have impacts on human health. Here we investigate the interaction between Zika virus and Mayaro virus, two emerging mosquito-borne pathogens currently circulating together in Latin America and the Caribbean. We find a major mosquito vector of these viruses—Aedes aegypti—can carry and transmit both arboviruses at the same time. Our findings emphasize the importance of considering co- and superinfection dynamics during vector–pathogen interaction studies, surveillance programs, and risk assessment efforts in epidemic areas.

A computationally efficient but accurate dynamic modeling approach for vapor compression systems is important for many applications. Nonlinear model order reduction techniques which generate reduced order models based on high fidelity vapor compression cycle (VCC) models are attractive for the purposes. In this paper, a number of technical challenges of applying model order reduction methods to VCCs are described and corresponding solution approaches are presented. It starts with a reformulation of a standard finite volume heat exchanger model for matching the baseline model reduction structure. Reduced order models for evaporator and condenser are constructed from numerical snapshots of the high fidelity models using Proper Orthogonal Decomposition (POD). Methodologies for system stability and numerical efficiency of POD reduced order models are described. The reduced order heat exchanger models are then coupled with quasi-static models of other components to form a reduced order cycle model. Transient simulations were conducted over a wide range of operating conditions and results were compared with the full order model as well as measurements. The validation results indicate that the reduced order model can execute much faster than a high-fidelity finite volume model with negligible prediction errors.

The small brown planthopper, Laodelphax striatellus, is a destructive pest insect found in rice fields. L. striatellus not only directly feeds on the phloem sap of rice but also transmits various viruses, such as rice stripe virus (RSV) and rice black-streaked dwarf virus, resulting in serious loss of rice production. RSV is a rice-infecting virus that is found mainly in Korea, China, and Japan. To develop novel strategies to control L. striatellus and L. striatellus-transmitted viruses, various studies have been conducted, based on vector biology, interactions between vectors and pathogens, and omics, including transcriptomics, proteomics, and metabolomics. In this review, we discuss the roles of saliva proteins during phloem sap-sucking and virus transmission, the diversity and role of the microbial community in L. striatellus, the profile and molecular mechanisms of insecticide resistance, classification of L. striatellus-transmitted RSV, its host range and symptoms, its genome composition and roles of virus-derived proteins, its distribution, interactions with L. striatellus, and resistance and control, to suggest future directions for integrated pest management to control L. striatellus and L. striatellus-transmitted viruses.

BACKGROUND An increasing number of medical journals are using social media to promote themselves and to communicate with their readers. However, little is known about how medical journals use Twitter and what their social media management strategies are. OBJECTIVE To understand how medical journals use of Twitter from a global standpoint, we conducted a broad, in-depth analysis of all the available Twitter accounts of medical journals indexed by major indexing services, with a particular focus on their social networks and content. METHODS The Twitter profiles and metadata of medical journals were analyzed, along with the social networks on their Twitter accounts. RESULTS The results showed that overall, publishers used different strategies regarding Twitter adoption, Twitter usage patterns, and their subsequent decisions. The following specific findings were noted. 1) Journals with Twitter accounts had a significantly higher number of publications and a greater impact than their counterparts. 2) Subscription journals had a slightly higher (2%) Twitter adoption rate than open access journals. 3) Journals with higher impact had more followers. 4) Prestigious journals rarely followed other lesser-known journals on social media. Additionally, an in-depth analysis of 2,000 randomly selected tweets from four prestigious journals revealed that The Lancet had dedicated considerable effort to communicating with people about health information and fulfilling its social responsibility by organizing committees and activities to engage with a broad range of health-related issues; The New England Journal of Medicine and the Journal of the American Medical Association focused on promoting research articles and attempting to maximize the visibility of their research articles; while the British Medical Journal provided copious amounts of health information and discussed various health-related social problems to increase social awareness of the field of medicine. CONCLUSIONS Our study used various perspectives to investigate how medical journals use Twitter and explored the Twitter management strategies of four of the most prestigious journals. Our study provides a detailed understanding of medical journals’ use of Twitter from various perspectives and can help publishers, journals, and researchers better utilize Twitter for their respective purposes.

Integrating renewable energy and energy storage systems provides a way of operating the electrical grid system more energy efficiently and stably. Thermal storage and batteries are the most common devices for integration. However, it is not clear which integrated storage system performs better in terms of overall economics. Ice storage has low initial and maintenance costs, but there is an efficiency penalty for charging of storage and it can only shift electrical loads associated with building cooling requirements. A battery's round-trip efficiency, on the contrary, is quite consistent and batteries can be used to shift both HVAC and non-HVAC loads. However, batteries have greater initial costs and a shorter life. This research presents a tool, using model predictive control and optimal sizing, and provides a case study for comparing life-cycle economics of battery and ice storage systems for commercial buildings that have chillers for cooling and an on-site photovoltaic system.

Thermal energy storage (TES) for a cooling plant is a crucial resource for load flexibility. Traditionally, simple, heuristic control approaches, such as the storage priority control which charges TES during the nighttime and discharges during the daytime, have been widely used in practice, and shown reasonable performance in the past benefiting both the grid and the end-users such as buildings and district energy systems. However, the increasing penetration of renewables changes the situation, exposing the grid to a growing duck curve, which encourages the consumption of more energy in the daytime, and volatile renewable generation which requires dynamic planning. The growing pressure of diminishing greenhouse gas emissions also increases the complexity of cooling TES plant operations as different control strategies may apply to optimize operations for energy cost or carbon emissions. This paper presents a model predictive control (MPC), site demonstration and evaluation results of optimal operation of a chiller plant, TES and behind-meter photovoltaics for a campus-level district cooling system. The MPC was formulated as a mixed-integer linear program for better numerical and control properties. Compared with baseline rule-based controls, the MPC results show reductions of the excess PV power by around 25%, of the greenhouse gas emission by 10%, and of peak electricity demand by 10%.

Small and medium-sized commercial buildings (SMCB) are significant demand response resources, and it is important to develop grid-responsive control algorithms that exploit those resources and create financial benefits for building owners and HVAC service providers. Furthermore, unlike large-sized commercial buildings, there is an opportunity to have universally applicable control solutions for many SMCBs since those buildings have a consistent HVAC system configuration: SMCBs are commonly served by multiple-staged air conditioning units controlled by their own thermostats. Despite the demand response potential and scalability, however, very few control solutions are available for SMCBs. Typical model predictive control (MPC) and heuristic control approaches for cooling load shifting that lower thermostat setpoints before an electric price jump are suitable mainly for large-sized commercial buildings where a continuous capacity modulation is possible, e.g., via dampers in variable air volume terminal units. However, those approaches can cause undesired, high peaks for SMCBs due to the nature of ON/OFF unit staging and narrow thermostat deadbands. This could discourage the use of advanced grid-responsive controls for SMCBs due to the concern of high demand charges, and has to be resolved. This paper presents a MPC solution that overcomes this challenge. It has a hierarchical MPC structure where an upper level MPC is responsible for electrical load shifting in response to an electric price signal while a lower level MPC is responsible for coordinating compressor stages to eliminate unnecessary peaks and follows the setpoints determined by the upper level MPC. Two one-month, comprehensive laboratory tests have been carried out to demonstrate load shifting and cost savings for the algorithm. Interesting trade-offs between energy efficiency and load flexibility were observed and are discussed, and lessons learned for applying MPCs for SMCBs are also presented.

Zeolite nanosheets can be used for the fabrication of low-defect-density, thin, and oriented zeolite separation membranes. However, methods for manipulating their morphology are limited, hindering progress toward improved performance. We report the direct synthesis (i.e., without using exfoliation, etching, or other top-down processing) of thin, flat MFI nanosheets and demonstrate their use as high-performance membranes for xylene isomer separations. Our MFI nanosheets were synthesized using nanosheet fragments as seeds instead of the previously used MFI nanoparticles. The obtained MFI nanosheets exhibit improved thickness uniformity and are free of rotational and MEL intergrowths as shown by transmission electron microscopy (TEM) imaging. The nanosheets can form well-packed nanosheet coatings. Upon gel-free secondary growth, the obtained zeolite MFI membranes show high separation performance for xylene isomers at elevated temperature (e.g., p -xylene flux up to 1.5 × 10 −3 mol m −2 s −1 and p -/ o -xylene separation factor of ~600 at 250°C).

Background An increasing number of medical journals are using social media to promote themselves and communicate with their readers. However, little is known about how medical journals use Twitter and what their social media management strategies are. Objective This study aimed to understand how medical journals use Twitter from a global standpoint. We conducted a broad, in-depth analysis of all the available Twitter accounts of medical journals indexed by major indexing services, with a particular focus on their social networks and content. Methods The Twitter profiles and metadata of medical journals were analyzed along with the social networks on their Twitter accounts. Results The results showed that overall, publishers used different strategies regarding Twitter adoption, Twitter use patterns, and their subsequent decisions. The following specific findings were noted: journals with Twitter accounts had a significantly higher number of publications and a greater impact than their counterparts; subscription journals had a slightly higher Twitter adoption rate (2%) than open access journals; journals with higher impact had more followers; and prestigious journals rarely followed other lesser-known journals on social media. In addition, an in-depth analysis of 2000 randomly selected tweets from 4 prestigious journals revealed that The Lancet had dedicated considerable effort to communicating with people about health information and fulfilling its social responsibility by organizing committees and activities to engage with a broad range of health-related issues; The New England Journal of Medicine and the Journal of the American Medical Association focused on promoting research articles and attempting to maximize the visibility of their research articles; and the British Medical Journal provided copious amounts of health information and discussed various health-related social problems to increase social awareness of the field of medicine. Conclusions Our study used various perspectives to investigate how medical journals use Twitter and explored the Twitter management strategies of 4 of the most prestigious journals. Our study provides a detailed understanding of medical journals’ use of Twitter from various perspectives and can help publishers, journals, and researchers to better use Twitter for their respective purposes.

The application of nanofiber (NF) and porous metal-organic framework (MOF) has increasingly attracted attention for the protection of public health. This composite platform provides the physical sieving of particulate matters (PMs) and capturing gases, serving as an outstanding filtering medium with lightweight and multifunctionality. Herein, process design and optimization are performed to produce a multifunctional membrane comprised NFs and MOF particles. Electrospinning/electrospray techniques are used to fabricate a hybrid membrane of poly(vinyl alcohol) NF and Fe-BTC as an adsorptive MOF on a macroporous nonwoven (NW). Three types of filters are prepared by varying the order of processing steps, that is, MOF/NF/NW, MOF+NF/NW, and NF/MOF/NW, to elucidate the effect of the fabrication process in the filtration of air pollutant. The optimal filtration performance is achieved in MOF+NF/NW system: the highest filtration efficiency (97%) and outstanding gas capturing efficiencies (≈60% and ≈35% decreases from initial NH

In direct H2O2 synthesis, the Pd-Au alloy was considered as a potential catalyst because of its much better performance compared to the prototype Pd; unfortunately, achieving both high activity and selectivity remains a challenge. Here, we synthesized nonconcentric Pd-Au NPs in which Au domain shells are formed only partially on Pd domain cores and tested them for direct H2O2 synthesis. It has three exposed regions of Pd, Au domains, and Pd-Au interfaces in a single NP (hence, a 3-in-1 strategy). Creating nonconcentric forms was demonstrated convincingly by density functional theory calculations. The nonconcentric Pd-Au particles exhibit high and well-balanced performances that are hard to achieve with traditional alloyed Pd-Au. The number of Pd/Au interfaces was found to be the key factor and thus was optimized by controlling the Au precursor concentrations. The hitherto underutilized structure of nonconcentric bimetallic alloys can be useful and thus should be more actively investigated for catalyst development.