Ad-hoc Solutions Research Articles

Extrinsic calibration of 2D laser rangefinders from perpendicular plane observations

Many applications in the fields of mobile robotics and autonomous vehicles employ two or more 2D laser rangefinders (LRFs) for different purposes: navigation, obstacle detection, 3D mapping or simultaneous localization and mapping. The extrinsic calibration between such sensors (i.e. finding their relative poses) is required to exploit effectively all of the sensor measurements and to perform data fusion. In the literature, most works employing several LRFs obtain their extrinsic calibration from manual measurements or from ad-hoc solutions. In this paper we present a new method to obtain such calibration easily and robustly by scanning perpendicular planes (typically corners encountered in structured scenes), from which geometric constraints are inferred. This technique can be applied to a rig with any number of LRFs in almost any geometric configuration (a minimum of two LRFs whose scanning planes are not parallel is required). Experimental results are presented with synthetic and real data to validate our proposal. A C++ implementation of this method and a dataset are also provided.

Hand gesture recognition with jointly calibrated Leap Motion and depth sensor

Novel 3D acquisition devices like depth cameras and the Leap Motion have recently reached the market. Depth cameras allow to obtain a complete 3D description of the framed scene while the Leap Motion sensor is a device explicitly targeted for hand gesture recognition and provides only a limited set of relevant points. This paper shows how to jointly exploit the two types of sensors for accurate gesture recognition. An ad-hoc solution for the joint calibration of the two devices is firstly presented. Then a set of novel feature descriptors is introduced both for the Leap Motion and for depth data. Various schemes based on the distances of the hand samples from the centroid, on the curvature of the hand contour and on the convex hull of the hand shape are employed and the use of Leap Motion data to aid feature extraction is also considered. The proposed feature sets are fed to two different classifiers, one based on multi-class SVMs and one exploiting Random Forests. Different feature selection algorithms have also been tested in order to reduce the complexity of the approach. Experimental results show that a very high accuracy can be obtained from the proposed method. The current implementation is also able to run in real-time.

FocusStack and StimServer: a new open source MATLAB toolchain for visual stimulation and analysis of two-photon calcium neuronal imaging data.

Two-photon calcium imaging of neuronal responses is an increasingly accessible technology for probing population responses in cortex at single cell resolution, and with reasonable and improving temporal resolution. However, analysis of two-photon data is usually performed using ad-hoc solutions. To date, no publicly available software exists for straightforward analysis of stimulus-triggered two-photon imaging experiments. In addition, the increasing data rates of two-photon acquisition systems imply increasing cost of computing hardware required for in-memory analysis. Here we present a Matlab toolbox, FocusStack, for simple and efficient analysis of two-photon calcium imaging stacks on consumer-level hardware, with minimal memory footprint. We also present a Matlab toolbox, StimServer, for generation and sequencing of visual stimuli, designed to be triggered over a network link from a two-photon acquisition system. FocusStack is compatible out of the box with several existing two-photon acquisition systems, and is simple to adapt to arbitrary binary file formats. Analysis tools such as stack alignment for movement correction, automated cell detection and peri-stimulus time histograms are already provided, and further tools can be easily incorporated. Both packages are available as publicly-accessible source-code repositories1.

Market Design Under Distributional Constraints: Diversity in School Choice and Other Applications

Distributional constraints are important in many market design settings. Prominent examples include the minimum manning requirements at each Army branch in military cadet matching and diversity considerations in school choice, whereby school districts impose constraints on the demographic distribution of students at each school. Standard assignment mechanisms implemented in practice are unable to accommodate these constraints. This leads policymakers to resort to ad-hoc solutions that eliminate blocks of seats ex-ante (before agents submit their preferences) to ensure that all constraints are satisfied ex-post (after the mechanism is run). We show that these current solutions ignore important information contained in the submitted preferences, resulting in avoidable inefficiency. We then introduce new dynamic quotas mechanisms that result in Pareto superior allocations while at the same time respecting all distributional constraints and satisfying important fairness and incentive properties. We expect the use of our mechanisms to improve the performance of matching markets with distributional constraints in the field.

Security and privacy in molecular communication and networking: opportunities and challenges.

Molecular Communication (MC) is an emerging and promising communication paradigm for several multi-disciplinary domains like bio-medical, industry and military. Differently to the traditional communication paradigm, the information is encoded on the molecules, that are then used as carriers of information. Novel approaches related to this new communication paradigm have been proposed, mainly focusing on architectural aspects and categorization of potential applications. So far, security and privacy aspects related to the molecular communication systems have not been investigated at all and represent an open question that need to be addressed. The main motivation of this paper lies on providing some first insights about security and privacy aspects of MC systems, by highlighting the open issues and challenges and above all by outlining some specific directions of potential solutions. Existing cryptographic methods and security approaches are not suitable for MC systems since do not consider the pecific issues and challenges, that need ad-hoc solutions. We will discuss directions in terms of potential solutions by trying to highlight the main advantages and potential drawbacks for each direction considered. We will try to answer to the main questions: 1) why this solution can be exploited in the MC field to safeguard the system and its reliability? 2) which are the main issues related to the specific approach?

The Emergence of E-Learning Needs in Participatory Re-Design of e-Service

Several research initiatives are nowdays focusing on the idea of “smart” cities or territories, where “smart” refers to the assumption that information technology would improve the quality of life in the city. In our work, we discuss the contribution we gave to Smart Campus, a research project aimed at creating a community that would enable the emergence of a virtual campus in a university town. Our focus was to improve the quality of the students' participation to the research project. Several interesting findings emerged from the work described in this paper, the most relevant being the importance given to functionalities replacing what students currently do with ad-hoc solutions using a range of unrelated services.

Utility-preserving privacy protection of textual healthcare documents

The adoption of ITs by medical organisations makes possible the compilation of large amounts of healthcare data, which are quite often needed to be released to third parties for research or business purposes. Many of this data are of sensitive nature, because they may include patient-related documents such as electronic healthcare records. In order to protect the privacy of individuals, several legislations on healthcare data management, which state the kind of information that should be protected, have been defined. Traditionally, to meet with current legislations, a manual redaction process is applied to patient-related documents in order to remove or black-out sensitive terms. This process is costly and time-consuming and has the undesired side effect of severely reducing the utility of the released content. Automatic methods available in the literature usually propose ad-hoc solutions that are limited to protect specific types of structured information (e.g. e-mail addresses, social security numbers, etc.); as a result, they are hardly applicable to the sensitive entities stated in current regulations that do not present those structural regularities (e.g. diseases, symptoms, treatments, etc.). To tackle these limitations, in this paper we propose an automatic sanitisation method for textual medical documents (e.g. electronic healthcare records) that is able to protect, regardless of their structure, sensitive entities (e.g. diseases) and also those semantically related terms (e.g. symptoms) that may disclose the former ones. Contrary to redaction schemes based on term removal, our approach improves the utility of the protected output by replacing sensitive terms with appropriate generalisations retrieved from several medical and general-purpose knowledge bases. Experiments conducted on highly sensitive documents and in coherency with current regulations on healthcare data privacy show promising results in terms of the practical privacy and utility of the protected output.

Querying moving events in wireless sensor networks

The detection and tracking of composite events in Wireless Sensor Networks often employ ad-hoc solutions that aim at detecting and tracking only specific types of events or use generic query languages that are not specifically built to manage events. We propose a new query language and an in-network query processing solution that enable the definition of queries to track and gather information from events, using wireless sensor networks. The proposed language provides clauses aimed at defining dynamic tracking tasks and the autonomous migration of the queries on the network, depending on the event mobility. We describe the query model and the language, discuss its implementation, and present the results of the comparison with a TinyDB-like approach. We show that our approach is scalable with event mobility and that it is more energy efficient than TinyDB-like approaches.

Towards an Automated BPEL-based SaaS Provisioning Support for OpenStack IaaS

Software as a Service (SaaS) applications fully exploit the potential of elastic Cloud computing Infrastructure as a Service (IaaS) platforms by enabling new highly dynamic Cloud provisioning scenarios where application providers could decide to change the placement of IT service components at runtime, such as moving computational resources close to storage so to improve SaaS responsiveness. Moreover, emergent Internet of Things (IoT) scenarios enable novel computing applications involving several heterogeneous smart objects interacting with each other. These highly dynamic scenarios call for novel Cloud support infrastructures able to automate the whole SaaS provisioning cycle spanning from resource management to dynamic IT service components placement, including software deployment, components re-activation, and rebinding operations. However, notwithstanding the core importance of these functions to truly enable the deployment of complex SaaS over IaaS environments, at the current stage only partial and ad-hoc solutions are available. This paper presents a support infrastructure aimed to facilitate the composition of heterogeneous resources, such as single Virtual Machines (VMs), DB services and storage, and stand-alone services, by automating the provisioning of complex SaaS applications over the widely diffused real-world open-source OpenStack IaaS. Collected experimental results show the effectiveness of parallel execution of deployment steps introduced by our solution and demonstrate its applicability and advantages in a real SaaS production testbed.

Experimental Comparison of Sensor Fusion Algorithms for Attitude Estimation

Inertial Measurement Unit is commonly used in various applications especially as a low-cost system for localization and attitude estimation. Some applications are: real-time motion capture system, gait analysis for rehabilitation purposes, biomedical applications, advanced robotic applications such as mobile robot localization and Unmanned Aerial Vehicles (UAV) attitude estimation. In all the mentioned applications the accuracy and the fast response are the most important requirements, thus the research is focused on the design and the implementation of highly accurate hardware systems and fast sensor data fusion algorithms, named Attitude and Heading Reference System (AHRS), aimed at estimating the orientation of a rigid body with respect to a reference frame. A large number of different solutions can be found in the literature, and an experimental comparison of the most popular is presented in this work. In particular, the algorithm based on the gradient descent method and the algorithm based on a nonlinear complementary filter are compared to a standard Extended Kalman Filter (EKF) with the aim to show that a general method can easily compete with ad-hoc solutions and even outperform them in particular conditions. In order to validate the estimation accuracy a Kuka robot is used to compute the ground truth. Moreover, in order to estimate the computational burden, the algorithms are implemented on an ARM-Cortex M4-based evaluation board.

“And Then, the Weekend Started”: Story of a WSN Deployment on a Construction Site

Wireless Sensor Networks (WSNs) are versatile monitoring systems that can provide a large amount of real-time data in scenarios where wired infrastructures are inapplicable or expensive. This technology is expected to be handled by domain experts, who perceive a WSN as a (promised to be) easy to deploy black box. This work presents the deployment experience of a WSN, as conducted by domain experts, in a ground improvement area. Building upon off-the-shelf solutions, a fuel cell powered gateway and 21 sensor devices measuring acceleration, inclination, temperature and barometric pressure were installed to monitor ground subsidence. We report about how poor GSM service, malfunctioning hardware, unknown communication patterns and obscure proprietary software required in-field ad-hoc solutions. Through the lessons learned, we look forward to investigating how to make the deployment of these systems an easier task.

A Survey of the Research on Future Internet and Network Architectures

The Internet was designed for academic use more than 40 years ago. After having been used commercially, many unpredictable requirements have emerged, including mobility, security and content distribution. In addition, the Internet has become so ossified that fulfilling new requirements is difficult. Instead of developing ad-hoc solutions, re-designing clean-slate Internet architectures has become a key research challenge in networking communities. This survey paper addresses key research issues and then introduces ongoing research projects from Japan, the United States and the European Union.

Land, Law and Policy Reform for the Management of Squatter Resettlement in Malaysia

This paper is to identify what are the factors amounting to squatter resettlement and how the law overcome this issue which has been unsolved problem in developing country. High volume of internal migration without adequate planning and support leads to urban problems such as squatter settlements, slum areas, traffic congestions, urban poor, urban sprawl, etc. Housing policies which focus primarily on legalizing the land tenure of residents, slum redevelopment and it involves the demolition of existing squatter’s resettlement and redevelopment of new resident. Land, law and policy reform for the management of squatter settlements in Malaysia is a research undertaken to explore the need to develop policies and legal mechanism to manage the issues relating to squatters in Malaysia. Post independence Malaysia witnessed influx of rural population to urban centers in pursuit of better opportunities in terms of employment, education, health and improved living conditions. This has impacted adversely on the urban environment owing to the pressure arising from the increasing demand for land from the population. Slums created by informal settlements are not mere problems that require adhoc solutions, but could be a result of lopsided and vested urban policies covering land ownership, unequal access to land, infrastructure provision and maintenance, and other socio-economic issues. Squatter settlement is becoming an increasing global concern that if left unchecked could culminate into a global crisis no less than global financial crisis.

The need for simulation in complex industrial systems

We discuss the concept of simulation and its application in the resolution of problems in complex industrial systems. Most problems of serious scale, be it an inventory problem, a production and distribution problem, a management of resources or process improvement, all real world problems require a mix of generic, data algorithmic and Ad-hoc solutions making the best of available information. We describe two projects in which analytical solutions were applied or contemplated. The first case study uses linear programming in the optimal allocation of advertising resources by a major internet service provider. The second study, in a series of projects, analyses options for the expansion of the production and distribution network of mining products, as part of a sensitive strategic business review. Using the examples, we make the case for the need of simulation in complex industrial problems where analytical solutions may be attempted but where the size and complexity of the problem forces a Monte Carlo approach.

On the modeling and generation of service-oriented tool chains

Tool chains have grown from ad-hoc solutions to complex software systems, which often have a service-oriented architecture. With service-oriented tool integration, development tools are made available as services, which can be orchestrated to form tool chains. Due to the increasing sophistication and size of tool chains, there is a need for a systematic development approach for service-oriented tool chains. We propose a domain-specific modeling language (DSML) that allows us to describe the tool chain on an appropriate level of abstraction. We present how this language supports three activities when developing service-oriented tool chains: communication, design and realization. A generative approach supports the realization of the tool chain using the service component architecture. We present experiences from an industrial case study, which applies the DSML to support the creation of a service-oriented tool chain. We evaluate the approach both qualitatively and quantitatively by comparing it with a traditional development approach.

Viper

The reliability of future processors is threatened by decreasing transistor robustness. Current architectures focus on delivering high performance at low cost; lifetime device reliability is a secondary concern. As the rate of permanent hardware faults increases, robustness will become a first class constraint for even low-cost systems. Current research into reliable architectures has focused on ad-hoc solutions to improve designs without altering their centralized control logic. Unfortunately, this centralized control presents a single point of failure, which limits long-term robustness. To address this issue, we introduce Viper, an architecture built from a redundant collection of fine-grained hardware components. Instructions are perceived as customers that require a sequence of services in order to properly execute. The hardware components vie to perform what services they can, dynamically forming virtual pipelines that avoid defective hardware. This is done using distributed control logic, which avoids a single point of failure by construction. Viper can tolerate a high number of permanent faults due to its inherent redundancy. As fault counts increase, its performance degrades more gracefully than traditional centralized-logic architectures. We estimate that fault rates higher than one permanent faults per 12 million transistors, on average, cause the throughput of a classic CMP design to fall below that of a Viper design of similar size.

Una aproximación multi-agente para el soporte al proceso de extracción- transformación-carga en bodegas de datos

Para brindar una solución adecuada en términos de robustez y auto-matización en el proceso de Extracción-Transformación-Carga (ETL por sus siglas en inglés) en bodegas de datos, en este artículo se presenta un modelo de sistema multi-agente que recopila las fortalezas de otros enfo-ques como son los wrappers y soluciones ad-hoc. Tal modelo considera la heterogeneidad y disponibilidad de las fuentes de datos, así como el carác-ter distribuido de los mismos. Para su validación se llevó a cabo una experimentación con datos tanto simulados como reales, la cual demostró no sólo su viabilidad técnica si no también su efectividad en cuanto a porcentaje de datos procesados y a tiempo para hacerlo.

Simultaneous isoform discovery and quantification from RNA-seq.

RNA sequencing is a recent technology which has seen an explosion of methods addressing all levels of analysis, from read mapping to transcript assembly to differential expression modeling. In particular the discovery of isoforms at the transcript assembly stage is a complex problem and current approaches suffer from various limitations. For instance, many approaches use graphs to construct a minimal set of isoforms which covers the observed reads, then perform a separate algorithm to quantify the isoforms, which can result in a loss of power. Current methods also use ad-hoc solutions to deal with the vast number of possible isoforms which can be constructed from a given set of reads. Finally, while the need of taking into account features such as read pairing and sampling rate of reads has been acknowledged, most existing methods do not seamlessly integrate these features as part of the model. We present Montebello, an integrated statistical approach which performs simultaneous isoform discovery and quantification by using a Monte Carlo simulation to find the most likely isoform composition leading to a set of observed reads. We compare Montebello to Cufflinks, a popular isoform discovery approach, on a simulated data set and on 46.3 million brain reads from an Illumina tissue panel. On this data set Montebello appears to offer a modest improvement over Cufflinks when considering discovery and parsimony metrics. In addition Montebello mitigates specific difficulties inherent in the Cufflinks approach. Finally, Montebello can be fine-tuned depending on the type of solution desired.

Parfm: Parametric Frailty Models inR

Frailty models are getting more and more popular to account for overdispersion and/or clustering in survival data. When the form of the baseline hazard is somehow known in advance, the parametric estimation approach can be used advantageously. Nonetheless, there is no unified widely available software that deals with the parametric frailty model. The new parfm package remedies that lack by providing a wide range of parametric frailty models in R. The gamma, inverse Gaussian, and positive stable frailty distributions can be specified, together with five different baseline hazards. Parameter estimation is done by maximising the marginal log-likelihood, with right-censored and possibly left-truncated data. In the multivariate setting, the inverse Gaussian may encounter numerical difficulties with a huge number of events in at least one cluster. The positive stable model shows analogous difficulties but an ad-hoc solution is implemented, whereas the gamma model is very resistant due to the simplicity of its Laplace transform.

Persistently Exciting Model Predictive Control for SISO systems

A formulation of Persistently Exciting Model Predictive Control (PE-MPC) for Single-Input Single-Output (SISO) systems is presented. PE-MPC is an extension of a conventional model predictive control where a Persistence of Excitation Condition (PEC) is included as inequality constraint, to allow for adaptive implementation and on-line tuning of the model. The PEC makes the PE-MPC feasible region non-convex. For SISO systems the non-convex region can be represented as the union of two convex regions. Therefore an ad-hoc solution of the PE-MPC optimization problem can be efficiently computed. This is done by exploiting the particular structure of the PEC constraint. Finally a numerical example of SISO sytem is given and several scenarios are simulated to analyze the PE-MPC properties.