János Sallai

• Vanderbilt University

A key component to enhancing reproducibility in the molecular simulation community is reducing ambiguity in the parameterization of molecular models used to perform a study. Ambiguity in molecular models often stems from inadequate usage documentation of molecular force fields and the fact that force fields are not typically disseminated in a forma...

A key component to enhancing reproducibility in the molecular simulation community is reducing ambiguity in the parameterization of molecular models. Ambiguity in molecular models often stems from the dissemination of molecular force fields in a format that is not directly usable or is ambiguously documented via a non-machine readable mechanism. Sp...

The paper introduces a visual programming language and corresponding web and cloud-based development environment called NetsBlox. NetsBlox is an extension of Snap! and builds upon its visual formalism as well as its open source code base. NetsBlox adds distributed programming capabilities by introducing two well-known abstractions to block-based pr...

Emerging smart services, such as indoor smart parking or patient monitoring and tracking in hospitals, incur a significant technical roadblock stemming primarily from a lack of cost-effective and easily deployable localization framework that impedes their widespread deployment. To address this concern, in this paper we present a low-cost, indoor lo...

This paper introduces NetsBlox, a visual programming environment for learning distributed programming principles. Extending both the visual formalism and open source code base of Snap!, NetsBlox provides two accessible distributed programming abstractions to simplify the process of creating networked applications: message passing and Remote Procedu...

Emerging smart services, such as indoor smart parking or patient monitoring and tracking in hospitals, incur a significant technical roadblock stemming primarily from a lack of cost-effective and easily deployable localization framework that impedes their widespread deployment.To address this concern, in this paper we present a low-cost, indoor loc...

In prior work, Sallai, et al. introduced the concept and algorithms of building molecular topologies through the use of a hierarchical data structure and the use of an affine coordinate transformation to connect molecular components. In this work, we expand upon the original concept and present a refined version of this software, termed mBuild , wh...

Event-driven programming is a popular methodology for the development of resource-constrained embedded systems. While it is a natural abstraction for applications that interface with the physical world, the disadvantage is that the control flow of a program is hidden in the maze of event handlers and call-back functions. TinyOS is a representative...

Molecular dynamics (MD) simulations play an important role in materials design. However, the effective use of the most widely used MD simulators require significant expertise of the scientific domain and deep knowledge of the given software tool itself. In this paper, we present a tool that offers an intuitive, component-oriented approach to design...

Systems and methods for estimating projectile trajectory and projectile source location are provided. A method for estimating location information associated with a supersonic projectile propelled from a source includes recording sound at a first location using a single microphone during travel of the supersonic projectile to produce an acoustic re...

The functionalization of nanoparticles with polymers to form “tethered nanoparticles” (TNPs) is a promising approach to control the structure and properties of nanomaterials. However, the vast landscape of possible building blocks makes predicting the final behavior of tethered nanoparticles a priori a challenging task. Concepts from the computer s...

In many mobile wireless applications such as the automated driving of cars, formation flying of unmanned air vehicles, and source localization or target tracking with wireless sensor networks, it is more important to know the precise relative locations of nodes than their absolute coordinates. GPS, the most ubiquitous localization system available,...

In many mobile wireless applications such as the automated driving of cars, formation flying of unmanned air vehicles, and source localization or target tracking with wireless sensor networks, it is more important to know the precise relative locations of nodes than their absolute coordinates. GPS, the most ubiquitous localization system available,...

In this paper we propose a distributed, low-power, self-organizing MAC scheme for low-power wireless sensor and control applications. In such applications, nearly periodic traffic needs to be handled so that the communication delays are minimized and the transmission is as predictable as possible. We propose Asynchronous Random Schedules with Colli...

The paper presents a smartphone-based shooter localization system. As muzzle blasts are difficult to detect at longer distances and consequently present higher false detection rates, the system relies on shockwaves only. Each sensor uses four microphones to detect the Angle of Arrival and the length of the shockwave. This information, along with th...

Over the past decade, wireless sensor networks have advanced in terms of hardware design, communication protocols, and resource efficiency. Recently, there has been growing interest in mobility, and several small-profile sensing devices that control their own movement have been developed. Unfortunately, resource constraints inhibit the use of tradi...

Many-core Graphics Processing Units (GPU) provide a high-performance parallel hardware platform on the desktop at an incredibly low cost. However, the widespread use of this computational capacity is hindered by the fact that programming GPUs is difficult. The state-of-the-art is to develop code utilizing the NVIDIA Compute Unified Device Architect...

A wireless sensor network-based wearable countersniper system prototype is presented. The sensor board is connected to a small helmet-mounted microphone array that uses time of arrival (ToA) estimates of the ballistic shockwave and the muzzle blast to compute the angle of arrival (AoA) of both acoustic events. A low-power radio is used to form an a...

Acoustic shooter localization systems are being rapidly deployed in the field. However, these are standalone systems---either wearable or vehicle-mounted---that do not have networking capability even though the advantages of widely distributed sensing for locating shooters have been demonstrated before. The reason for this is that certain disadvant...

Mobile phones are gaining popularity as sensing platforms. They already come with a set of built-in sensors, such as GPS, accelerometer, microphone and radio, enabling interesting applications. Furthermore, several systems exist where external sensors are interfaced with mobile phones to monitor medical conditions or support environmental sensing,...

The paper presents a novel sensor fusion technique to shooter localization using a wireless network of single-channel acoustic sensors. The unique challenge is that the number of available sensors is very limited. The first contribution of the work is an approach to estimate the miss distance of the shot and the range to the shooter from a single s...

Several localisation algorithms exist for wireless sensor networks that use angle of arrival measurements to derive node position. However, there are limited options for actually obtaining the angle of arrival using resource‐constrained devices. In this paper, we describe a technique for determining node bearings based on radio interferometric angl...

Over the past decade, wireless sensor networks have advanced in terms of hardware design, communication protocols, resource efficiency, and other aspects. Recently, there has been growing interest in mobile wireless sensor networks, and several small-profile sensing devices that are able to control their own movement have already been developed. Un...

Mobile wireless sensors require position updates for tracking and navigation. We present a localiza-tion technique that uses the Doppler shift in radio transmission frequency observed by stationary sensors. We consider two scenarios. In the first, the mobile node is carried by a person. In the sec-ond, the mobile node controls a robot. In both appr...

Recent advancements in low-power wireless communication technologies allow for rapid deployable embedded monitoring applications with a deployment lifetime of several weeks of months. In this work, we present a work-in-progress wireless audio streaming solution that uses a network of small wireless microphone arrays to form a distributed steerable...

This work-in-progress paper introduces a new hardware plat-form for wireless sensor networks, summarizes the new chal-lenges it creates for software development and describes a toolchain being developed to meet those challenges. The hardware platform is based on a low-power FPGA as op-posed to a traditional microcontroller. The FPGA config-uration...

Wireless ad-hoc sensor networks are typically deployed randomly in space to gather information about the physical world. In these spatially random sensor networks, one of the fundamental problems is precise node localization along with the key requirement to keep node cost at minimum. Existing radio interferometry-based node localization techniques...

Several localization algorithms exist for wireless sensor networks that use angle of arrival measurements to estimate node position. However, there are limited options for actually obtaining the angle of arrival using resource-constrained devices. In this paper, we describe a radio interferometric technique for determining bearings from an anchor n...

The paper introduces a new hardware platform for wireless sensor networks built around a Flash FPGA. The most important feature Flash FPGAs offer is their duty cycling support; they can wake up from sleep in one microsecond with now current spike and they preserve their configuration as well as the application state. Moreover, the new node provides...

Today, RF based indoor node localization and tracking techniques predominantly rely on received signal strength (RSS), proximity information, or some sort of a priori mapping of the RF environment. However, due to nonideal RF propagation caused by effects such as reflection, refraction, scattering and multipath, as well as the dynamically changing...

The paper introduces a novel technique for the bearing estimation of radio sources that can be used for the precise localization and/or tracking of RF tags such as wireless sensor nodes. It is well known that the bearing to a radio source can be estimated by an array of antennas typically arranged in a circular manner. The method is often referred...

Fusing spatially distributed observations in wireless sensor networks or asset tracking in a shipyard are just two-example applications where the location of radio nodes needs to be known. Localization and tracking of wireless nodes have been an active research area, yet a universal solution has not emerged so far. This paper introduces a novel met...

Localization and tracking of wireless nodes have been active research areas in robotics, mobile ad-hoc networks, and wireless sensor networks. While several phenomena have been utilized for this purpose, RF signals have many advantages. Signal strength and time-of-flight are the two typical ways of extracting range information. Recently, radio inte...

Many wireless sensor network applications require knowl- edge of node placement in order to make sense of sensor data in a spatial context. Networks of mobile sensors require position updates for navigation through the sensing region. The global positioning system is able to provide localization information, however in many situations it cannot be...

Precise indoor localization of wireless nodes remains a challenge today. While there are radio-frequency (RF) meth- ods that offer significant advantages, the balance between accuracy, range, and cost is suboptimal for many applica- tions. Radio interferometry has been shown to be effec- tive outdoors, however, its applicability indoors has not bee...

Radio-interferometric ranging is a novel technique that al- lows for fine-grained node localization in networks of inexpensive COTS nodes. In this paper, we show that the approach can also be applied to precision tracking of mobile sensor nodes. We introduce inTrack, a cooperative tracking system based on radio-interferometry that features high acc...

Wireless sensor network has drawn increasing attentions in recent years due to its wide range of applications. Often deployed in hostile environments, wireless sensor network is particularly vulnerable to malicious attacks. Thus security becomes a critical issue. This paper studies the security support for source authentication for broadcasting in...

Location-awareness is an important requirement for many mobile wireless applications today. When GPS is not appli- cable because of the required precision and/or the resource constraints on the hardware platform, radio interferometric ranging may oer an alternative. In this paper, we present a technique that enables the precise tracking of multiple...

Time synchronization is a crucial component of a large class of sensor network applications, traditionally implemented as a standalone middleware service that provides a virtual global time to the application layer. While this approach is simple and robust, it suers from two im- portant drawbacks: first, power aware operation is cumbersome to imple...

An ad-hoc wireless sensor network-based system is presented that detects and accurately locates shooters even in urban environments. The localization accuracy of the system in open terrain is competitive with that of existing centralized countersniper systems. However, the presented sensor network-based solution surpasses the traditional approach b...

The prevailing paradigm in the regime of resource-constrained embedded devices is event-driven programming. It offers a lightweight yet powerful concurrency model without multiple stacks resulting in reduced memory usage compared to multi-threading. However, event-driven programs need to be implemented as explicit state machines, often with no or l...

We present a mobile acoustic beacon based sensor node localization method. Our technique is passive in that the sensor nodes themselves do not need to generate an acoustic signal for ranging. This saves cost, power and provides stealthy operation. Furthermore, the beacon can generate much more acoustic energy than a severely resource constrained se...

Fine-grained geographic localization of nodes is essential for an extensive range of distributed sensor applications. To compute geographic coordinates, localization algorithms commonly use pair-wise distance estimates between nodes. In this paper we present a noise tolerant acoustic ranging mechanism for wireless sensors that employs digital signa...

An ad-hoc wireless sensor network-based system is presented that detects and accurately locates shooters even in urban environments. The system consists of a large number of cheap sensors communicating through an ad-hoc wireless network, thus it is capable of tolerating multiple sensor failures, provides good coverage and high accuracy, and is capa...

This paper introduces a novel method for bearing estimation based on a rotating antenna generating a Doppler shifted RF signal. The small frequency change can be measured even on low cost resource constrained nodes using a radio interferometric technique introduced previously. Measuring the Doppler shift at two known locations provides a bearing es...

A large class of sensor network applications requires that sensors have knowledge of a common reference time (virtual global time). Typical use cases of a time synchronization service are coordinated action (e.g. a group of sensors coordinate to acquire sensor data at the same instant) or data fusion (i.e. timestamped sensor readings from multiple...