Rigorous Dynamic Model-Based Economic Design of the Injected Pultrusion Process with Controllability Considerations

Developing the concept of linear function: one student’s experiences with dynamic physical models

The West African city of Accra, home to over two million of Ghana’s 25 million residents, serves as the country’s political capital and economic centre. Since gaining independence in 1957, Ghana has made significant investments in road infrastructure and services. Road transportation accounts for the majority of passenger and freight traffic in the country. This paper discusses current street design practices and some of the challenges faced by designers and residents in Accra. After providing background information on the city’s urban form, transportation system and street design agencies, case studies are conducted on three of Accra’s thoroughfares. These case studies evaluate how current design practices, based on US and British standards, meet the needs of different street users. Each of the selected roads serves a different purpose within Accra’s transportation network. The case studies revealed that pedestrians and other non-motorised transport (NMT) users are largely neglected by current design practices.

Current seismic design practice related to integral bridge girder-to-cap beam connections allows little or no lateral seismic load to be distributed beyond the girders immediately adjacent to the column. However, distribution results from several large-scale tests have shown that the distribution of column seismic moment typically engages all the girders. An approach utilizing simple stiffness models to predict distribution in integral bridge structures is presented in detail; distribution predictions based on grillage analyses also are compared. The experimental results and the analytical results from the stiffness and grillage models show that current design methods related to vertical load distribution are sufficiently accurate. However, when applied to the distribution of lateral load, similarly obtained results reveal that current design practice does not appropriately account for the amount of load that is distributed beyond the girders adjacent to the column to the nonadjacent girders. The current practice leads to excessive girder-to-cap connection reinforcement, increased girder depth, unnecessarily high seismic mass, and increased construction cost. Finally, this paper makes recommendations for more appropriate distribution of seismic lateral load in integral bridge superstructures.

This paper addresses the inverse dynamics of a 4-d.o.f. parallel robot, H4. Simplified inverse dynamics models have been proposed so far in which the inertia of a rod is neglected. Computation of the inertia of the rod was a heavy load for past computers and, hence, the simplified inverse dynamics were useful for online computation. However, owing to the recent great progress in computer hardware, online computation of the full dynamics is no longer a heavy load for modern computers. Therefore, a detailed inverse dynamics model of H4 is proposed in this paper. The Newton–Euler method is adopted for generating inverse dynamics solutions for H4 which have four (S–S)2 (two spherical–spherical) chains in each rod. In order to evaluate the proposed inverse dynamics model, three controllers are tested: (i) PD controller, (ii) PD controller with velocity feed-forward and (iii) dynamic compensation controller based on the proposed dynamics model. The experimental results are presented and analyzed. It is also shown that the simplified dynamics model can be used without clear deterioration of control quality.

A dynamic dehumidifier model for simulations and control of liquid desiccant hybrid air conditioning systems

These days, the topic on the sustainable building has become one of the most important concerns in the academic studies, construction industries, as well as governmental agencies. Sustainability in the building sector has raised the attention towards a new concept called net-zero energy buildings (NZEBs). With regards to the development of Malaysia’s buildings sectors, the government has realised the undesirable effects of inefficient of energy usage by demonstrating their efforts in Construction Industry Transformation Programme (CITP) 2016-2020. Commonly, healthcare buildings are among the greatest energy consumers of any institution and the extensive use of various medical equipment, mechanical ventilation of this building has caused a high level of carbon emission. Hence, by concentrating on these issues, NZEBs become an important concept to be implemented in healthcare buildings. However, the awareness of NZEBs in Malaysia is still low and the construction industry in Malaysia still unaware of NZEBs. This paper aims to investigate the current design practices of healthcare buildings in Malaysia as well as the architect’s understanding of NZEBs through preliminary investigation among architects. Literature was reviewed and pilot studies by using semi-structured interviews were conducted. The results uncover that some green practices related to the design practices in healthcare buildings has been carried out and some of these practices are similar to the NZEBs design practices even though the term of ‘NZEBs’ is not being used. It is predicted that the paper will provide a basic knowledge for future research in NZEBs for healthcare buildings, challenges of NZEBs implementation and designing NZEBs for healthcare buildings in Malaysia.Keywords: Net zero energy buildings, Healthcare building, Current green design practices, Malaysia

Combinations of dynamic models and Geographical Information Systems (GIS) have a vast potential to solve problems. Deficiencies and advantages of GIS and dynamic models are described. A multifaceted description of complex systems allows three different types of combining dynamic models and GIS. Different classes of dynamic models are used within these combinations. These are: — complex aggregated dynamic feedback models (e.g. like those of Odum, Forrester or of the AEAM work1), — simple generic dynamic models (in particular object oriented models) — models of physics based on partial differential equations (e.g. those for heat conduction or dispersal of noise or transport of gaseous pollutants). The model dynamics are combined with GIS held “base maps” to produce time series of maps, so called “Dynamic Maps”. Base maps combine spatial features which are locally important for the dynamic process and are used to either modify or even form the dynamics. Different types of models need different types of GIS-held base maps and are adequate for different types of problems. This paper is based on a number of actual applications of one of these combinations; an overview is provided on potential applications of the whole new approach.

Certain elements of contemporary design practice strike the authors as rather meager, especially in regard to the decision-making stage, allowing little or no time for contemplation and thus causing design to become a prompt reaction rather than an extended reasoning. This co-written article examines the lack of time in design practice and with it the lost appreciation of previous ways of thinking and making. Thus, it investigates ways of moving forward with craft, seeking to develop the bridging between designerly knowing and craftsmanship by reintroducing concepts of craft (dwelling, care) into current design practice. In doing this we hope to encourage designers to explore how previous knowledge can be utilized to develop an alternative mode of progress for design – leading us to propose an evolutionary approach to design.

This paper presents the current state of microfluidic design from a practitioner's perspective. The capture of microfluidic design practice was facilitated through a combination of industry survey and expert interviews, allowing the authors to draw out models for microfluidic design. Exploration of the current practice of microfluidic design showed that formal design methodologies were not in use. This research has also found that sub-section interactions have been addressed in an inadequate fashion by current design practices. The work presented in this paper outlines the scope for further research in the development of a formal design methodology for microfluidics.

The idea of the iconic turn relates to a perceived increase in the use of images and icons for communication purposes during the 19th and particularly the 20th century. More recently, various theorists have further argued that digital media and specifically hypertext media are a catalyst for this development. The multi-linear approach of hypertext, the increasing integration of pictures, moving image and animation in the Internet as well as the dominance of the graphic user interface (GUI) are seen as major indicators for a paradigm shift towards a dominancy of the image for the purpose of information exchange. The argument culminates in the idea that the envisioned change will come at the expense of alphabetic text and will amount to the end of the use of prose for communication purposes.<br> This thesis questions such notions concerning the iconic turn with respect to digital writing. It compares them to the status quo of design practice particularly in digital media networks such as the Web and reveals fundamental discrepancies between theory and this practice. It will be demonstrated that hypertext and specifically the Web to the contrary are still very much text-based environments, strongly built on both the diachronic and synchronic qualities of language and the two-dimensional expression that is possible through alphabetic writing. This work also explains how proponents of a pictorial approach towards digital communication have been misled by early day phenomena and wishful thinking.<br> This thesis draws from cognitive science, cultural history, information theory and linguistics as well as from current design practice. Design practice plays an important role in the discussion regarding digital writing and the iconic turn as it is held partly responsible for the shift from alphabetic text to the image by some of the theorists ar guing in favour of image writing. A new understanding of the role of the designer in the context of digital writing will be proposed because, as it will be demonstrated, notions of graphic design as a catalyst for the decline of the alphabet are based on a fundamentally flawed perception of the role of the designer in digital media.

It is widely recognized that the building sector largely contributes to the total European energy consumption with a 40% influence on the total assessed energy uses. To this regard the EPBD recast Directive promotes nearly zero energy buildings (nZEB) for the public and the private sector as a mandatory requirement by 2020. Given the low energy efficiency of old buildings, concerns about the state of the existing building stock should be seriously considered as most of the energy consumption is attributable to the existing buildings. Additionally, residential buildings are often seen as long-term assets, setting thus a low replacement rate, approximately 1% per year in Europe, of old buildings by new ones. To this regard, larger energy savings can be achieved with the energy retrofitting of the existing building stock, rather than with the construction of relatively small proportion of new high performing buildings. Therefore, the refurbishment of the existing building stock has to be primarily planned and accomplished in order to achieve a timely reduction on the buildings energy consumption. Concerning this, the EPBD recast, as policy driver for reducing European energy use in buildings, has been representing the first and main legislative reference. According to it Member States must ensure that minimum energy performance requirements are set with a view of achieving at least cost-optimal levels for buildings, building units and building elements by means of a comparative methodology framework applied to new constructions and existing buildings undergoing major renovations. The methodology specifies how to compare energy efficiency measures in relation to their energy performance and to the cost attributed to their implementation, and how to apply these to selected reference buildings with the aim of identifying cost-optimal levels of minimum energy performance requirements. A cost optimal level is defined as the energy performance level, which leads to the lowest cost during the estimated economic lifecycle of the building. A measure is considered cost-effective when the cost of implementation is lower than the achievable benefits, during the expected life of the measure. This type of analysis allows defining energy renovation scenario based on their energy and economic optimum. Within the complex scenario described above, this Ph.D. thesis aims to provide a methodology for the definition of energy retrofit scenarios to be applied to existing buildings, based on the use of dynamic building simulation models. The methodology targets the existing building stock given the large energy savings that can be achieved from existing buildings. It builds on an energy and economic assessment of energy efficiency measures applied to different building typologies. The energy and economic assessment are respectively carried out by means of dynamic building simulation and a cost-optimality approach. The cost optimal analysis was chosen for the aim of this study for its systematic approach in defining energy retrofit interventions based on their energy and economic optimum. The term scalable is used for defining the methodology as the studied energy retrofit scenarios can vary depending on the of the study. Two main scales of buildings can be distinguished: building stock or single buildings. When retrofit interventions are studied to be applied to wide portion of the building stock, as for example at national level, representative building models are used. They correspond to reference buildings representative of a certain building typology, construction age and geographic location. Within this thesis, a methodology for their definition was defined and various reference buildings for the Italian context were created. On the contrary, when it is necessary to study specific and customized retrofit measures, a single existing building is modelled. In this case, compared to the case of the reference buildings, larger quantity of data and a higher degree of detail are necessary. These building models are customized based on the existing buildings characterization (e.g. building envelope, system, etc) and when applicable, based also on data from monitoring. To this regards, when detailed information about the building real operation from monitoring is available, the building model need to be calibrated based on measured data. For a model to be calibrated, the building energy consumption predicted by the simulation program, has to match the consumption measured from monitoring. Calibrated models can be used for comparing the baseline situation of the building (calibrated and not retrofitted) with other simulation results relative to the application of building renovation interventions. To this regard, within this Ph.D. thesis, a literature review on the most common calibration techniques currently in use for the calibration of building models was conducted. Additionally two case studies were calibrated by means of two different approaches: a trial and error approach and an optimization-based calibration. For both scale of buildings (building stock and single buildings), dynamic building simulation was employed for the energy assessment. Building simulation application has expanded since mid-‘70s building simulation as an attempt to emulate reality. To date, it is much more common to employ building simulation in post construction or advanced building design phases rather than in early phases. In particular building simulation is frequently used for the prediction of energy savings by assessing energy retrofit interventions on existing buildings. To this regard, given its wide application and the high level of detail of the analysis performed (dynamic analysis), building simulation was chosen within this thesis, as a tool for the energy assessment of buildings and of the relative energy renovation interventions. Finally, the economic assessment of the energy retrofit measures was carried out by means of the cost optimal methodology, as defined by the EPBD recast. The methodology allowed defining energy renovation interventions based on their economical and energy optimum. The Directive requires to define different packages of energy efficiency measures, which can be applied to reference representative buildings but also to single and existing building for energy and economical assessments. The energy assessment of a building can be carried out with analytical or simplified methods, but dynamic building simulation is strongly suggested, as performed within this thesis. For the economic assessment, the global cost method was employed based on the calculation method of the Standard EN 15459 as advised by the EBPD. The global cost method considers, for each energy efficiency measure, the initial investment, the sum of the annual costs for every year (including energy costs) and the final value, all with reference to the starting year of the calculation period. In order to define different energy retrofit solution and set the minimum energy performance requirements, within the Ph.D. thesis, the cost optimal approach was applied to both the considered scale of buildings: to the building stock scale with three reference buildings, and to the single buildings scale with two calibrated buildings. A set of energy efficiency measures was defined and applied to the case studies for evaluating the financial and energy performance gap between the cost-optimal solutions and nZEB levels, respectively. For the building stock, different energy retrofit solutions are defined as final outcomes. Given the use of representative models (reference buildings), the retrofit solutions can be replicated to several buildings, among the same building typology. In this sense, different energy retrofit solutions can be established. On the other hand, for single buildings, the energy retrofit solution studied is specific and customized barely to the analyzed case study

Catalytic naphtha reforming is a crucial process in producing gasoline or aromatic compounds. The characteristic of two production modes gives rise to different economic optimization and control objectives. In the present work, we design an economic model predictive control (EMPC) with a production mode switching strategy to cope with these problems. First, a rigorous dynamic process model is established to simulate the naphtha reforming process. Then, we formulate different economic objective functions and simplify the process model for each production mode, and also enable the EMPC controller to switch the production mode automatically according to empirical equations. Three case studies are presented to test the performance of our proposed control strategy. The results show that the designed EMPC controller with production mode switching can successfully overcome the economic disturbances and improve the production profits in different production modes. In addition, it also has a fast response time to drive the system to a new economic optimal operating point.

BackgroundGiven the heterogeneity of stroke, it is important to determine the best course of motor therapy for each patient, i.e., to personalize rehabilitation based on predictions of long-term outcomes. Here, we propose a hierarchical Bayesian dynamic (i.e., state-space) model (HBDM) to forecast long-term changes in a motor outcome due to rehabilitation in the chronic phase post-stroke.MethodsThe model incorporates the effects of clinician-supervised training, self-training, and forgetting. In addition, to improve forecasting early in rehabilitation, when data are sparse or unavailable, we use the Bayesian hierarchical modeling technique to incorporate prior information from similar patients. We use HBDM to re-analyze the Motor Activity Log (MAL) data of participants with chronic stroke included in two clinical trials: (1) the DOSE trial, in which participants were assigned to a 0, 15, 30, or 60-h dose condition (data of 40 participants analyzed), and (2) the EXCITE trial, in which participants were assigned a 60-h dose, in either an immediate or a delayed condition (95 participants analyzed).ResultsFor both datasets, HBDM accounts well for individual dynamics in the MAL during and outside of training: mean RMSE = 0.28 for all 40 DOSE participants (participant-level RMSE 0.26 ± 0.19—95% CI) and mean RMSE = 0.325 for all 95 EXCITE participants (participant-level RMSE 0.32 ± 0.31), which are small compared to the 0-5 range of the MAL. Bayesian leave-one-out cross-validation shows that the model has better predictive accuracy than static regression models and simpler dynamic models that do not account for the effect of supervised training, self-training, or forgetting. We then showcase model’s ability to forecast the MAL of “new” participants up to 8 months ahead. The mean RMSE at 6 months post-training was 1.36 using only the baseline MAL and then decreased to 0.91, 0.79, and 0.69 (respectively) with the MAL following the 1st, 2nd, and 3rd bouts of training. In addition, hierarchical modeling improves prediction for a patient early in training. Finally, we verify that this model, despite its simplicity, can reproduce previous findings of the DOSE trial on the efficiency, efficacy, and retention of motor therapy.ConclusionsIn future work, such forecasting models can be used to simulate different stages of recovery, dosages, and training schedules to optimize rehabilitation for each person.Trial registration This study contains a re-analysis of data from the DOSE clinical trial ID NCT01749358 and the EXCITE clinical trial ID NCT00057018

The application of endovascular aortic aneurysm repair has expanded over the last decade. However, the long-term performance of stent grafts, in particular durable fixation and sealing to the aortic wall, remains the main concern of this treatment. The sealing and fixation are challenged at every heartbeat due to downward and radial pulsatile forces. Yet knowledge on cardiac-induced dynamics of implanted stent grafts is sparse, as it is not measured in routine clinical follow-up. Such knowledge is particularly relevant to perform fatigue tests, to predict failure in the individual patient and to improve stent graft designs. Using a physical dynamic stent graft model in an anthropomorphic phantom, we have evaluated the performance of our previously proposed segmentation and registration algorithm to detect periodic motion of stent grafts on ECG-gated (3D+t) CT data. Abdominal aortic motion profiles were simulated in two series of Gaussian based patterns with different amplitudes and frequencies. Experiments were performed on a 64-slice CT scanner with a helical scan protocol and retrospective gating. Motion patterns as estimated by our algorithm were compared to motion patterns obtained from optical camera recordings of the physical stent graft model in motion. Absolute errors of the patterns' amplitude were smaller than 0.28 mm. Even the motion pattern with an amplitude of 0.23 mm was measured, although the amplitude of motion was overestimated by the algorithm with 43%. We conclude that the algorithm performs well for measurement of stent graft motion in the mm and sub-mm range. This ultimately is expected to aid in patient-specific risk assessment and improving stent graft designs.

Aqueous xanthan gum solutions are non-Newtonian fluids, pseudoplastic fluids possessing yield stress. Their continuous mixing is an extremely complicated phenomenon exhibiting non idealities such as channeling, recirculation and stagnation. To characterize the continuous mixing of xanthan gum solutions, three dynamic models were utilized: (1) a dynamic model with 2 time delays in discrete time domain, (2) a dynamic model with 2 time delays in continuous time domain, and (3) a simplified dynamic model with 1 time delay in discrete time domain. A hybrid genetic algorithm was employed to estimate the model parameters through the experimental input-output dynamic data. The extents of channeling and fully-mixed volume were used to compare the performances of these three models. The dynamic model parameters exerting strong influence on the model response were identified. It was observed that the models with 2 time delays gave a better match with the experimental results.